MTN ********

I have tried countless times to contact MTN telling them how I got a contract sim via buy mondo I was promised a plan for 20GB a day 20GB at night! I needed up getting 5GB only which was not the initial agreement I went further to complain to mtn and stopped using the sim now I have to pay an amoun of R1600 for something that I stopped using over a year back? Mtn is used to ******** people and getting away with it