Incorrect data allocated.

I had a contract with nashua mobile. It was for a samsung galaxy s4 on cell c, I got 100mins, 100sms and 1gb data. Since autopage have taken over this contract, I have only been receiving 100mb. My bill has always been R399 for the first 18 months , now it ranges between R800 and R1200. I have reported this to the call centre three times, and have been to the Pietermaritzburg branch twice, this matter has still not been resolved. Please ciuld someone help me to get the correct data bundle, and the money I was incorrectly billed for refunded to me.