Account cancelled but keeps on being billed!!!

I am so unhappy with Telkom and their administration is shocking to say the least. I have given them an instruction to cancel my ADSL & line rental account the first week in June. This in anticipation of the fact that we were moving to a new area in Pretoria. I gave them notice and went into the Centurion branch on the 6th of June and it was all logged on their system to be cancelled on the 30th of June. THEN as a precaution I went back to Centurion brance on Saturday the 27th of June to confirm - and it was confirmed to me that the cancellation will go through by the end of June. Come the first week in July and I've once again received a Telkom statement. The debit order is to go through again end of July. I immediately phone the call center and there they promise me that the account has now been cancelled and July will be the final bill. I then once more went into the Telkom branch - this time Woodlands and they confirm once more. Today I received another statement with different figures that I will be billed again. I mean really - this is shocking. The number has been completely deactivated but they keep on billing me. WHAT CAN I DO? This is really shocking Telkom..