Why should I pay for MTN mistakes. Worst customer and branch service ever.

The worst service ever from both branch and customer service. I took a new 50G simcard only contract and they dispatched a simcard which is wrong, as the number given to me is *** on the new simcard and at the branch they say it's a wrong simcard, the allocated number and simcard do not correspond with what is on the system and I have to pay R160 to make a sim swap to get the right number. Currently I don't have data but have a data contract that I am expected to pay monthly. The simcard is not working, it only receives calls. I am thinking of cancelling the contract as it's still under 1 month since I took it. The branch wants R160, customer service is referring me back to be the branch. Why should I pay for a mistake that was caused by MTN. This is one of the worst customer service I have ever had as I asked for the supervisor but was actually sent to another agent to repeat what I had told the other agent. I doubt I will recommend MTN contract to anyone ever.