Penalized for not loading data

MTN KICKS ME OUT OF MTN NETWORK EVERY TIME MY DATA IS FINISHED. I CANT USE MY AVAILABLE AIRTIME. I LOGGED A CALL TWICE WITH THEM AND WAS TOLD THEY'VE ESCALATED THE MATTER WITH THEIR TECHNICAL SUPPORT TEAM, I'M STILL WAITING TO DATE. I'M GETTING PENALIZED FOR NOT BUYING DATA. WHY AM I PAYING MY CONTRACT IF I DON'T GET ANY SERVICES FROM THEM.