Bad service delivery

I have a contract with mtn. A data contract had no problem with them until now. I had a 2gb a month contract then on the first night of receiving my new 2gb for the month. After the first day I checked my balance then everything was gone. I called to enquire about this then they just gave me the run around. They also increase there billing with out informing me didn't even receive a statement up untill now. This is the reason why I changed network cause it wasnt the first time it happen to me. <br> <br> All I want is the service that I pay for.