MTN issued an already utilised number on the MTN network.

I am a contract Vodacom customer, having ported from MTN in 2005. MTN has re-issued my number on a pre-paid contract on the MTN network,. This means that my mobile number is now registered on both the MTN and Vodacom database. When someone calls me from an MTN registered mobile number, the call is not directed to me but to the pre-paid sim holder. Surely this should be *******. This occurred in January 2025. I have tried to report this to MTN, through the call centre and via a MTN shop, but up until today I have not been successful. This shared mobile number is also a significant risk for my security. Can some-one please assist.