I need to change my banking details for the monthly debit order, I dont use the phone myself my son uses the phone, There is no way to change the bank details or change the debit order

I need to change my banking details for the monthly debit order, I dont use the phone myself my son uses the phone, There is no way to change the bank details or change the debit order. I didnt have the number on hand but have the account number and there voice prompt says cannot help and hangs up the call. I get the number but because I am calling from another number the call gets hung up and I get text messages from a chatbot that tells me it cant help me. There is no customer care email address just basically get lost we have you trapped in the account so we will do what we want.