Inability to allocate payment

My account has been paid via stop order from my bank for the past year and this month my payment was not allocated to my account. According to the agent I spoke to Aahq *** my reference was incorrect, but it was the same 16 digit card number as many months before. But now according to both the agent and his team leader Lee-anne there is no way to correctly allocate my payment. Not only have I now received messages saying my account is in arrears but also my credit score is now being affected. I cannot for one moment believe that a company of this size has not one person that cannot allocate this payment correctly. Not an accountant or clerk that can check a bank statement or account. But not only am I told to refer the issue to my bank, but the arrogance to say I need to make additional payment. Lee-ann's words were that they don't deal with stop orders, but yet they deal with eft on a daily basis. And all a stop order is is an automated eft. They can allocate that if a reference is incorrect but not a stop order. I believe this is an issue of not wanting to help, and now I have to deal with a negative listing even when I am not at fault. I await your reply