Data charges on MTN

I have a problem and do not agree with the MTN data. <br> They charge me for data on a galaxy that the contract was paid up and then they contact me and told me they will give me 2GB for R99 per month. I agree and told them that I want them to stop at 2GB.<br> Well almost for a year and a half everything was ok and now I get charge for R7000.00 data. This galaxy was never been use this much and now that I do not agree and only paid for the account that I agree and ask them to look into the problem.<br> They cut my cell and all the other devices I have problems with. Not once did they contact me to sort this out, know we just put your cell off.<br> How do we sort out problems if no one help you or try to contact me?<br> I am a good customer and always pay me account but now that I have a problem and do not agree they have no problem to just cut me off.<br>