120gb for R299 more like 20gb

I took out a contract from MTN the my choice 10gb, It was stated you get 40gb in the day and 80gb at night for R299, wow what a deal but I have only received 20gb in the day and 10gb at night, I mailed and Facebook messaged MTN for 2 weeks now, only reply is that the matter is being looked at, I pay my bill, but 2 weeks and no concrete answer? How is this fine.