Can’t do a sim swap

I have a review under Vodacom of my experience when I was getting a Vodacom phone contract and I am back with another review. I had the contract and when the term ended I requested to go back to prepaid. The phone I had was using a micro sim, I got a new phone which uses a nano sim meaning I can’t insert my initial sim, I bought a nano sim, got it registered and tried to do a sim swap which wasn’t a success, called Vodacom for assistance and I was told my number is under contract and they can’t do a sim swap unless if I buy a contract sim, what an inconvenience cause I’ve already bought a sim and you are now telling me I’m on contract whereas I have also switched to prepaid. I guess I’ll just have to lose my Vodacom number since they aren’t willing to assist me and just want to inconvenience me.