Data disappears and I receive a HUGE bill!!!

I have made calls with regards to my ever increasing account and data disappearing. When the MTN store called in I was told it takes a couple of days to escalate the complaint. Its about a month now and I have had not feedback with regards to my complaint. From and monthly account of basically just the basic charges on my account and using about 1 Gig of my 2 Gig bundle suddenly I receive an account of hundreds of rands. Previous month the account was R1600+. This month's ***!!!!! Not possible!! I will not pay this account. This needs to sorted out PLEASE. I have also logged network problems. No reply from mtn too!!! Some days I can not even connect at all due to bad signal. How can I run up a R4000+ bill!<br> All our local papers in futures the same negative reports. Why is mtn not sorting this out?? <br> I also took a new contract out- I have been waiting now for two weeks and the sim has not been rica'd!!! Upon collecting the new phone I also did not receive ANY documentation for myself! ? <br> Reference Nrs received: ***. C6602 W13.1. ***5. RQ. ***