Operator fail to suspend sim card, major account

On the 11th of January my p[hone was ******. I contacted the call centre in order to have the sim suspended immediately. The call centre operator informed me that the sim was suspended but he actually only made a note on the system and did not suspend services. During the time that I phoned to request suspension and when I did the sim swop more than R9 000 was charged on the account. Altech Autopage is billing me for the full amount. They should take responsibility for the amount spend during the time that they failed to suspend the services. I have tried numerous times to contact the call centre but either they do not answer or the put the phone down in your ear. Emails to customer service have also not produced any progress on the matter.