Insufficient Data loaded for My contract

I have upgraded my contract to a 20 Gig promo last month i received my full 20 Gig this month i received 10 gig + 5 gig Plus 2.5 Gig Promotion which is not what i signed up for. i called the Call Centre they logged a fault for me with Ref: 1- ********** 0814 which is now resolved and advised my data will be loaded withing 48 hours it has not been loaded when i call the Call centre they want to logged another fault stating that as far as they aware data was loaded. i am not willing to pay for something i never signed up for however am now told that they will charge me to cancel. i have experienced bad service before with MTN however my loyalty to the brand has nothing to offer me as a client but terrible service