Continuous Pathetic Service

I changed my bank details in March. I was advised that it would only be effective the following month, end April. I did a manual payment end March. This month my old account was debited again and there is no funds in that account. Went to the Cape Town store this morning and was told by Clint September that the account was not changed on ur system. He then refused to change my bank details as he wanted a letter from my bank and I refuse to go through all this trouble. The manager, Vernon cannot be approached as he told me he cannot assist me everytime I have a problem. How pathetic of a store manager. Please assist urgently.