URGENT ASSUSTANCE REQUIRED NOT RECEIVING CALLS

I would like someone from management in the technical department to contact me urgently regarding an issue with my incoming calls for over 3 weeks now! On Wednesday 23 October I stopped receiving incoming calls on my number 083*******. My calls are going through to someone else's phone whom I do not know. I do not have any call diverts on my phone. When someone tries to contact my number it goes through to a vodacom number 076******** The lady who answers is getting very annoyed as she is receiving all my calls. She eventually gave me her number and she informed me that she apparently got her phone from Pep stores on the same day that I stopped receiving my calls and to this day my calls are still going to her. It doesn't even go to my voice mail it goes to her mailbox. I have been pushed from pillar to post by MTN for over 3 weeks now and I'm still NOT getting my calls. The latest ref number I have is SMC/***. I was advised to got to an mtn store for assistance which I did and they opened up another ticket which is the above ref number. I have been dealing with Jade at the MTN store in Dayan Ave Boksburg. I am extremely fed up with this as I'm paying for a service for which I am not receiving and no one seems to know what is going on or how long it will take to sort out. I would appreciate URGENT assistance to get this issue resolved as I need my phone to function. My calls continue to go to the vodacom number listed in my email. I have been a customer of MTN for many, many years and I cannot believe this is the service from a leading network!