MTN does nothing about *****

My MTN number was recycled and given to someone else, due to inactivity. This person then got my contacts on WhatsApp and started ****ming the people on there for money, pretending to be me. We called MTN twice to try and stop the number. The one rep said they blocked the number on the system, but in shop today they confirmed that person **** to me, it's still active. I have screenshots from people they tried to ****, I messaged them to stop, the ****mers then phoned me and threatened to KILL me. Police didn't care, I could just do an affidavit there and take it to an MTN shop, as advised by the MTN rep. There they also could do nothing. They gave me the ***** line number. Who informed me they could do nothing. So MTN can take the number away because they are not making money off me, but they are unable to take the number away when it's used for ******** activities. They advised me to open a case at police or get lawyers. AGAINST WHOM DO I OPEN A CASE? They won't give me the details of the ****mers. What a clown company.