No service paying angry customer!

Its been a week now without being able to make calls or receive, i cant even call MTN from my phone because of "No service", been in store to get help but i got told that they were migrating my sim card, another person told me my sim card is old and needs to be changed so its affecting my service, how? I don't know. I call in from a different network and no one knows what the problem is and they have the audacity to still send me my bill for the month. While fixing the problem please cancel my contract!