MTN ****** me of two months minutes and data

I been with MTN forever and upgraded recently. When the contract was upgraded the package included bonus minutes and data. after the upgrade for two months there was no bonus data or minutes allocated to my number. I eventually required on month three and it took six different call being sent from pillar to post every time I called. eventually for July bonus data and minutes were added but they are refusing to refund the two months bonus data and minutes that they did not allocate. If I did not complain, they wouldn't have even loaded for this month. MTN have rules that are to favour them and they ****** me daylight as I took the contract based on the minutes and data that was promised but not given.