MTN IS USELESS

I took out in June a contract for laptop at mtn. The deal was for 4G day and 8G night. Inomly received it for the first month, the last 3 months I did not receive the data omly 1G and when I complain they took the 1G of. It is now 3 months that I did not got any data but they took my money every month for the contract. I am very dissappointed in MTN and I want this resolve asap