TAKING OFF ACCOUNT LIMITS

I had an MTN account with Nashua Mobile as my service provider. When they stopped doing Cellular, I was transferred to MTN. At this stage all my limits were taken off my account without my knowledge. I have a cell phone account and a data ****le. My data ****le is a R109 contract/month. IN the past 4 years of having this contract - when I have used all the data it stops working until the new month. Last month it just carried on because it is now \an open line"as the call centre tells me. How can they change my contract like this? I now have a bill of R743.93 on a R109 contract.This is completely unacceptable. I want MTN to deal with this complaint.<br> My cell phone also used to have a limit of about R800 but I see my Credit limit is now R7200 on my account. PLEASE I need somebody to sort this out and as the call centre would not help me I am trying this avenue. <br> """