Stop Debiting my acc

I have had 2 data contracts with Cell C and have been happy and they have been debit my account with no fail. Now the 2 years is up the just started debiting my account with a higher amount when i called to find out i was told that because the contract time was over the will now be charging me the normal price for the data sim card than the special rate i was paying, then they told me that because i am a valued customer they will revert back to debit me for the special price and will give me extra data for my trouble. its been 3 months now and they are still debiting ridiculous amounts. and when i call them, i am told that the manager from retentions will call me back, but i am still waiting. Kriyaan Naidoo from Cell C, i am still waiting for your call, all i want from Cell C is for you guys to stop debiting my account i will find another service provider. cause you have promised and promised and nothing has happened.