Mismanaged Billing/Accounts suspended my number

I am registered on a TOP UP contract, last week Wednesday the 20/05/2015 i received an SMS stating that i exceeded my limit of R2156.00 and my outgoing will now be suspended. I ignored because I am on a TOP UP contract but guess my outgoing has been suspended since then I am very furious because MTN doesnt even have a back staff or system to help with customer queries. My number is suspended since last week I work far from home and incase of emergency I cant even send an SMS. My MTN account is up to date I have never missed out on a payment and I now Therefore will not be making a payment because of the inconvenience and suspended service. MTN used to be the best service provider but guys you lost it all now the worst. I hope to receive some feed back ASAP and my number off suspension.