INCORRECT PREMIUM CHARGED

I upgraded my contract with MTN in July 2014 - this contract is with a Samsung Galaxy S 3 Mini phone. I have been to the MTN customer care counter in Hemingways Mall numerous times (actually ... both MTN stores in the Hem. Mall) and have asked them to PLEASE remove the BIS and credit me with the refund due to me. <br> <br> My contract (Samsung Galaxy S3 Mini) is R199.00 per month, yet I am being billed odd amounts between R258 and R337 per month.<br> <br> Please can someone help me to sort this out? I am SUPER FRUSTRATED! Please direct me where to go, or who to phone to get my account problem sorted out, because I am going to the wrong place, and calling the wrong people ... <br> <br> I want this issue sorted out ASAP. Please MTN - now is the time to step up and actually care for your customers!!!<br> <br> Adele Foster.<br>