Bad Service

I placed a complaint last Month on Hello Peter about my billing issue that i have, i was billed about R4700 last month and incurred bank charges for this. Ithen called the call centre & was told that a mistake was done and 100Gb was loaded on my account and it will be reversed ,i got an sms a day later saying that my query has been resolved. This morning i got sms saying that my account will be debited R3722.26, why is this if my account was fixed. this is ridiculos, i've had issues with my account ever since i took this contract with Mtn. i need this issue to be fixed or just cancel my contract because clearly i am not a valued customer.