MTN Unfairness To they Customers

Last Year around October i signed up for the 40 GB day and night package but to find out that i was only getting 20 GB , so i have been struggling to get assistance with MTN because all they have been doing when i call 083135 they keep givin me excusing . either the contract is not in PDF format or that i should go back to the store and ask them to make adjustments. I mean for a paying customer i believe all they should have done is change my package to the correct one.