MTN Sky Lite Data Problems

Myself and my husband upgraded in December 2017 and we both took the MTN Sky Light package and data booster 2GB @ R1699 per month. Since the first month we have not received the correct data and after a couple of highly frustrated telephone conversations and a few tickets I am now at the end of my line. Each month we receive 2 sms's stating that our accounts has been credited with 5gb and 2gb, but we only receive 5gb. Last night I check my balance and switched my data off specifically to check my balance this morning. The data balance at the time was 11.87gb, this morning my data balance was 16.87gb. I phoned MTN today and after 30 minutes on the phone and being cut-off and then again a 20 minute call, I was told that I did in fact received my 7gb, but my balance last night was 9.87gb. I really do not understand what happened to the 2gb! Next month I am going to take a screenshot of my balance before I switch off my sata for the night. However on my husbands contract I am being told that he only receive 5gb per month and not 7gb, but he receive the sms's stating that he should receive 7gb. His balance last night was 25mb and the morning it was 5.25gb. Can someone at Mtn please assist us with this issue?