Phone Blacklist

Late 2018 I bought a phone off OLX, the seller guided me through the phone and removed his google account.

the phone worked well until around April 2019. the phone lost network I contacted Telkom, thinking it was a network problem, and ported to Vodacom and it worked for a month, later it lost network. when I contacted Vodacom I was advised that the phone was blacklisted, I have them the complete story of the sale and asked me to complete a form. Vodacom came back to me and advised that the phone cant be un-blacklisted as its blacklisted by MTN. after contacting MTN I was told to go to the police station and report it and send back the relevant affidavit. after doing so i'm being told they cant help me.

Clearly the seller committed ***** by selling me the phone in order to claim for a new one. I'm now sitting with a dummy phone and a ******* of R3000.

if MTN cant help why did they say I need to go to the police station, and waisted so much of my time.

I need a solution to this, either the phone gets unblocked of I need the details of the seller and I will get him arrested.