Continued billing!

I have two complaints. Firstly, with approx 2months left on my account, I visited Telkom in The Atrium, Overport. I intended to change my bank account details, and after giving all my new details i was told that my account details had been changed successfully, only to find out that the following month the money continued being taken out from my old account, which didn't have enough funds. Due to this i was in arrears and ended up paying double what I had to. I had done so without any complain. I visited the Telkom Store in Westwood Mall, so as to officially end my account after my 24Month contract was complete. I was told that my contract was over only to find out that Telkom is still deducting money from my account and the contract is still active. I'm very annoyed. Please sort your nonsense out.