Sim swap - NO service

After months of bad service I am struggling with MTN AGAIN!!!!!! I asked for a sim swap in MTN Tygervalley on Wednesday afternoon because I bought a new phone. I received the new sim and was told that the old one would stop working within 24 hours and then I can switch over to the new one. I called 808 yesterday afternoon around 17:00 and was told it was still pending. I called again this morning and was told it was still pending but the lady escalated it, should have been done around 14:00. I called again at 14:30, was told again it is pending AND THAT I SHOULD GO TO A STORE TO GET IT DONE!!! HOW IS THIS EVEN POSSIBLE? My husband did the very same thing at the same time at Vodacom and his new sim has been working since yesterday afternoon as promised. I have been threatening for months to close my MTN account and I think I now have reached a stage where you leave me no choice. I can't stand MTN's non existent service anymore! If I do go back to a store it will be to close my account and find another service provider.