Bad Customer service all the way

I have been a customer with MTN and have since lost my phone , I have been trying to do a sim swap with them without any success , I have been to 3 of theirs stores and no one sims to be able to help me even thou when they look at their systems the number is registered or Rica,rd on my name . And no one can explain why they cant do a sim swap for me. I have registered for college and other stuff using the same number and now you can under my frustration as i cant even access most of my assignments .