Complete Disregard for My Billing Issue

i have a data contract with altech and a cap set at 800.00. In Feb 2015 I used up my data and my account was actually suspended. I called them to add an extra gig and happiness as I was able to use my account. When that gig got depleted I called them to add another 500 rand on my account over and above my limit so I could continue using the ****le. shock and horror I got a bill for 7000+ for the month. I called, queried and was told someone would get back to me. No one ever did. I followed up myself two months ago and got an email saying my case had been closed and a one liner \My Limit is unreliable". Called again and was told there are no caps on data. Argued that when I have depleted my data"