Bad very bad service.

I have upgraded from 5Gigs to 20 Gigs day time and 20 Gigs at night. Since I have upgraded in January, I still receive the five Gigs that I was on initially. Despite two calls that I have made on January and February nothing has changed. I still run out of data on the 15th of the month like it used to when I was using 5Gigs. More over for the past 2 months I haven't receive any billing statements and no explanation from Telkom. They always ask at the end of the call to rate them and their service. On all two occasions I rated them badly and still no call from. I have paid the money for 20gigs of data per month on January February and March and they still give me 5 Gigs of data. Please help me guys. How do I cancel them and retrieve the money that I have paid them extra? I cannot tolerate this any more. I have been deceived by Telkom and want out. I will try and explore Mweb. Plz help me. I want out but we have just signed a new contract with them.