Monthly Data Receiving Short 10GB

I took out a contract in November 2017 it was a Sim -Only Data It was an MTN Mega deals weekend

The deal was 30GB Any time and 20 GB Night Express a total of 50GB

Since November 2018 I am receiving 10GB short for Any time I am receiving the following Night Express 10GB Night Express 10GB MTN black Friday 10GB MTN 10GB

I have been to MTN La lucia mall MTN since December 2017 and dealing with Shireen at ********** and told it will be rectified at the end of the month it is now March 2019 still not rectified

I have also reported it to the call centre reference 1- ********** 6946 and still nothing has been sorted out

This is totally unacceptable that have been battling now for 4 months to get it sorted out but they take the money every month