Impossible Sim Swap

I upgraded my contract at my local MTN store at the Campus. They neglected to advise that I needed a nano sim and would require a sim swap. I found the instructions online and acquired a replacement sim and attempted a swap. *Nothing works*. They're supposed to send you a OTP which is valid for 15 minutes, but they send it to you after 20 minutes, once it's already expired. After try 20 when you finally get one in time, they then respond and tell you that the swap was unsuccessful, please phone 808. When you phone your call-centre you're told that they can't help you at all with sim swaps, you need to go to a store. My local store burnt down the day after I upgraded. So much incompetence all-round, I now need to waste my time hunting down another store just to complete a silly sim-swap because none of their systems actually work.