Mtn provided me a contract with a simcard that is not working and they are billing me.

I received my MTN contract phone on the 31 December. The simcard has never worked not even once.i called MTN numerous times and they keep telling me to wait 24hrs. I have waited for almost a month and I have now received a bill that shows that the simcard that isn't working is being billed. What am I paying for because the simcard is not working? Mtn please dort this mess out!