call centre messing me up!

I called mtn on the 15 july toask about my contract expiry. I spoke to Akhumzi and he told me to call on de 22 Aug, when my contracts end. Last week I called to found out how much was invoiced for aug, I asked again from the lady I was speaking to, she said, no call on the 24th because cancellation is only operating on week days. I called on monday de 24th, spoke to Nomalitha she said she was logging for me to the cancellation dept, it will take 2-5 woking days. I decided to call today, to check on the progress. I. Just spoke to a guy now, he tells me it will take 30 day for the cancellation to be done & I'll need to pay for the month of Aug. OMG this is not happening. Besides 1 incedent, I hav worked well with mtn but now I'm dissappointed with this run around and different stories. I'm not paying for Sept, I want this contract cancelled and my sim reverted to prepaid that's all I want, end of story. I'm so dissappointed and angry at this.