Cell phone cut off for no reason

About 18 months ago I signed a contract with Nashua Mobile. A year later, my contract was handed over to Altec Autopage. Initially with Nashua, I had put a R30 credit limit on my account and when I was reaching that limit, I received an SMS notifying me of the limit approaching. Once with Altec, I continued using my phone as I always had. On Friday afternoon my phone stopped working - I was unable to phone out, receive messages or connect to the Internet. On Saturday my girlfriend went into Altec and asked them to see what the problem was. She was told my R30 limit was reached and that my phone had been blocked. She requested that the R30 limit be lifted and my phone unblocked and was told it would be unblocked in 2 hours. This morning I went into Altec myself since my phone was still blocked. When querying why this was the case, I was told all Nashua customers had this problem and there was nothing they could do except request that the line was unblocked and hope for the best. I was told I should have received an SMS telling me I'd reached my limit but I hadn't. I think this is shocking service and would like something done as I feel Altec's service way below the expected standard