Handed over to CSS for an account i do not have with MTN

So MTN handed me over to CSS for an account i don't even have. I've had contracts with them in the past,the last one I had I paid off and cancelled with them last year April. Surprisingly when I call them they can see the account is long paid off and cancelled but 14 months later they handed me over? For what exactly? For your faulty systems? The call centre confirms that I'm on pre paid and they don't understand why I was handed over. I mean how do you run a business by ruining people's profiles? It's really unacceptable. Now my credit profile is messed up thanks to you. Fix this and fix it NOW!!!