Waiting over a week for a sim swap!!!

Just over a week ago I upgraded my cell phone contract with MTN. I was told that my new phone required a nano sim meaning that I would not be able to use my new phone until a sim swap had been completed and processed. Initially I was told that it would take between 2 and 24 hours for the swap to be processed... that was a week ago. Four days after the first sim swap attempt I was asked to return to the MTN store to fetch a different sim card as the MTN employee suspected I might have been given a faulty one, but 4 days after getting the new sim I'm still waiting. I've been a loyal MTN customer for almost a decade and I've never had problems with completing a sim swap before (I've done one in the past), so why is it an issue this time around? I'm now sitting with a new phone that's completely useless unless I'm in an area with wifi. How much longer am I expected to wait?