My mother has Alzheimer's and has been in a home for many years. I am an appointee for DWP and her pensions are paid into my account and then I pay care home fees and any other expenses she incurs. She has a post office bank account but they closed that type of account and she had no way of opening another. This has not been a problem for a good few years but out of the blue HMRC has discovered she has overpaid tax and sent a crossed cheque in her name. How can I cash this ? I don't have POA.