Poorest service

I'm been a customer for over ten years now and thus is the worst I have ever seen. I requested a early contract termination of which the amount I was given, I paid it but on a follow up call to discover that I was credited R18000 of which later changed to me owing R11000. The 11000 that they can't tell what is it for. To my surprise a debit oder was run on that 11000 that they can't tell me where or what is it for...