Help! Changing a bank account as an appointee (Dept for W&P) when over a certain amount?

[ShmooBooMoo]

Mum was made third party mandate on her mother's bank accounts (current and savings) at HSBC when she moved into a care home some years ago (in mother's name but mum buy things for her/ pay her contribution to care home fees).

Mum's mother's only income is state pension and more recently pension credits (no private pension or other non-benefit funds coming in at all) has dementia and the Dept for W&P have recently made my mum an appointee for her mother. She has a BF57 document. Mum went to the bank to inquire about changing the accounts to bring them in line with her position as appointee and the bank said that because there is more than £2000 in the bank my mum will have to see a solicitor and apply to the Court of Protection. How to proceed (and can solicitor's fees be paid from mum's mother's account as mum could not afford it).

My mum hates calling the Dept for W&P as she finds it hard to explain properly and get direct answers (sometimes told conflicting info!) I think she will have to ring them. She really was given no guidance as to how to proceed with re to what to do (just handed the BF57, really).

BUT, my question is: could my mum (if she can find a bank to open an appointee account - someone online said they had no joy with any bank apart from Halifax ) can mum close the HSBC accounts and open an appointee account with Halifax, or will she be made to jump through hoops?
It feels further complicated by the fact mum's mother has two accounts with HSBC...

Mum wants to be honest, straight and do things properly but she has no idea how to proceed since this info from the bank... She gets wrapped up in knots when she calls the Dept for W&P...all this is new to her and she feels like they speak a foreign language at times... She doesn't want this to drag on or cause issues (the care home is pushing for contribution to fees to be paid by SO but if mum is third party mandate with bank and appointee with Dept. for W&P, things aren't tallying....)

Any one here who can advise as to the next step?

Thanks so much...