I am an extremely frustrated MTN customer

I am an extremely frustrated MTN customer. My contract is for R199 per month, yet MTN has been deducting far more than what was agreed. In one month, I was charged R398 and later told I still owe R160. When I called, I was informed that I had a spend limit of R800+, something that was never explained when I signed the contract. I requested for the limit to be reduced to R0, and MTN confirmed that the change was made. However, this month I was again charged R398, and I now supposedly owe over R1000. When I followed up, I was told that my spend limit was still R800+ — meaning my previous request was ignored. I am fed up with this ongoing issue. It is unfair and feels like MTN is exploiting customers by overcharging and failing to correct their own errors. MTN, please fix this urgently, refund the incorrect deductions, and confirm that my limit has been set to R0 permanently. ***