MTN CONTRACTS ARE NOT WHAT THEY AGREE

Mtn has the worst customer service there is.Upgraded one of my 4 contracts to just data 10 g day an 10g night and they made it all night time bundels20 g and 2 day and not that what is stated on the contract when called them they said go to the mtn shop done this 4 times now 5 months later nothing just fill in forms at Jacaranda center mtn who originally gave the contract bad service nothing have been done .what must i do paying for somthing i don't get.