My phone started not receiving calls on SIM 2 then data stopped working

My phone started not receiving calls on SIM 2 then data stopped working. I switched SIM card s to another network something. I was to take it to a Vodacom repair centre which I did. Only to be told that they can fix it because it's blacklisted. I have been told to go to the police station to unblacklist that I bought and have been the only one using. I can't be inconvenied like this. I still have the receipt, box and accessories. They can take the phone and deal with the ups and downs. As I waited a full week only to be told it can be fixed.