Data bought and given via contract disappearing

I have a data contract with MTN which gives me 2 gig every month. I receive it on the 12 th of every month. Last month it was finished a week after I got it and I very seldom use my laptop and the data for it. I bought another 2 gig and a week after it it was gone and as I said I use my laptop seldom. I mostly use my data on my phone to browse the internet and facebook. I went to MTN Cape road PE asking that they must find out where my data disappeared to. I was told by the data guy that it is better to phone 808 which I did and was told that I would have the report within 2 days - that was about a month ago and I still don't have it! My phone's data is also disappearing much quicker than my telkom contract phone which I am using much more for internet than my MTN phone. I am very disappointed in MTN and will not renew my contracts with them!!