I hold joint power of attorney for an old family friend who has dementia.

She owns several rental properties and her affairs are not that straightforward, so it can involve a fair amount of work.

As she already had both an accountant and a financial adviser, we kept them because she's known them for years.

The trouble is neither firm is any good. The accountant filed her tax return late and so she incurred a fine. The financial adviser rarely responds to our emails.

We would dearly like to sack them and get more helpful and competent replacements. 

However, we understand there are certain rules for making such changes when you are an attorney, rather than just acting on your own behalf.

Surely it must be allowed though when attorneys feel it’s warranted. What process do we need to follow to get rid of the current accountant and adviser and get better ones?

Power of attorney: My family friend with dementia already had an accountant and financial adviser she's known for years - the trouble is neither is any good

Tanya Jefferies, of This is Money, replies: Your deference to your elderly friend's past relationship with these professionals is understandable, but it sounds like your patience has run out.

It would seem sensible to keep records of complaints, and any efforts to address things with the existing firms, before you give them polite written notice their services are no longer required.

Experts will give you a detailed take on what to do below. First, you will know this, but for the sake of other readers Lasting Power of Attorney is a legal failsafe for people who can no longer fend for themselves.

Appointing someone you trust, usually a family member or friend but sometimes a paid professional, to take control of your affairs if you fall ill is a relatively straightforward business. People often do it at the same time as they draw up a will.

There are two types of LPA, covering money and health, and you can get one or both if you are 18 or over and have the mental capacity to do so. The system is run by the Office of the Public Guardian, which also handles complaints if anything goes wrong.

In legal jargon, the person doing the appointing is the 'donor', and those appointed - often more than one person is chosen - are 'attorneys', who can take over for you if it's ever necessary.

One important issue is to decide if attorneys can act 'jointly', and therefore have to agree on all decisions, or 'jointly and severally', meaning they can make decisions independently from one another where that is more practical. It's obviously helpful if they know each other and are on good terms.

We asked Step, the industry body for inheritance professionals like lawyers and financial advisers, to answer your question. Two Step members have responded below about how attorneys can end relationships with poorly performing firms.

Holly Miéville-Hawkins, partner in the court of protection team at Anthony Gold Solicitors, replies: Attorneys are not obliged to keep a financial adviser or accountant who is letting them down simply because the donor chose them, but the donor's wishes remain an important factor when deciding whether a change is in their best interests.

Section 4 of the Mental Capacity Act 2005 sets out several factors that attorneys must weigh up when deciding whether a change is in the donor’s best interests.

Holly Miéville-Hawkins:  Attorneys should discuss the concerns with the donor if they are still able to express a view

They include the donor’s choice of adviser or accountant, any beliefs or values that may have influenced their decisions, the views of anyone interested in their welfare, and the views of anyone the donor asked to be consulted, including other professional advisers if relevant.

Attorneys should discuss the concerns with the donor if they are still able to express a view. They must also consider the views of any co-attorney before making a decision.

If they have been appointed jointly, all attorneys must agree before a decision can be made.

If they have been appointed jointly and severally, each attorney can act independently, but should still take each other's views into account.

If, having considered these factors, the attorneys decide that a change is in the donor's best interests, they can appoint new advisers.

Once a new accountant and financial adviser have been chosen, attorneys should give the previous firms formal notice and set up written terms of engagement with the new ones.

Ask the outgoing firms for a handover, including recent investment reports, tax returns and other relevant information, to keep things running smoothly.

Robin Melley, managing director of Matrix Capital Financial Planning, replies: Attorneys are under a duty to act in the donor's best interests, and that includes reviewing whether their professional advisers remain suitable.

If the attorneys are unhappy with the service from an accountant or financial adviser, they should start by raising their concerns with them and give them a chance to put things right.

Attorneys should choose professionals with experience of working with attorneys or deputies as well as vulnerable clients.

A deputy is someone appointed by the court to manage the affairs of someone who has lost mental capacity and does not have an attorney appointed.

It's worth asking prospective advisers about their experience of working with attorneys and deputies, and how they communicate and make decisions when someone is acting on another person's behalf.

Check that any independent financial adviser is authorised and regulated by the Financial Conduct Authority.

As this case involves a donor with dementia who owns rental properties, attorneys should look for an adviser who won't just focus on investments.

The starting point should be financial planning, such as working out cash flow and future costs.

This helps balance competing priorities, such as covering care costs now while still protecting money for the future.

A good adviser will also check the rental portfolio still makes sense for someone who has lost mental capacity, make sure future care costs are covered, and make sure money and assets are arranged in a tax efficient way.

The best outcomes are often achieved where the financial planner, accountant and solicitor work together on a coordinated long-term plan covering care funding, tax and estate planning.

Attorneys should keep a paper trail explaining why they decided to change the accountant and financial adviser and why they chose the replacements.

This will prove valuable if the decision is ever questioned by family members, the donor, or the Office of the Public Guardian.