AWFUL SYSTEMS IN PLACE AT ACCOUNTS DEPARTMENT

My Son-in-law left for Canada in 2020. He gave me power of attorney to sort out all his affairs. He got an email from MTN and noticed that the debit is still going off his account even though he went to MTN Store to cancel it. They person took the money for the cancellation period and told him that no more debits will go off the account. The money is still going off the account. Do you guys not have any processes in place there? This is ridiculous. I phone the accounts department now and they said I have to go into the branch and change his account into my name. I DO NOT WANT TO CHANGE HIS ACCOUNT TO MY NAME. I JUST WANT THEM TO REFUND HIM ALL THE MONEY SINCE 2020. The lady then told me my son-in-law has to give me an affidavit allowing me to sort out his account. WHY MUST HE DO THAT. I HAVE POWER OF ATTORNEY. She said she cannot help me at all. Can the director please come back to me regarding this matter. His cell number is ***