Unauthorized blacklisting.

I am having a contract with MTN,i upgraded and did not get a handset but the SIM card. I bought a handset from another store and used the MTN sim in it. on the 4th of September i experienced network issues and i went to the Wonderpark branch to inquire. I was informed that my handset was blacklisted on 2019.04.01. They requested an affidavit and a copy of my identity card of which i gave. I then received an unblacklisting email. I then lost my handset the following day and went to the Kolonade branch to blacklist it. I am sitting here struggling with the insurance as MTN has blacklisted my handset and according to the insurance investigators MTN alleges that i obtained the handset **********ly. How do you explain the blacklisting of a handset without my knowledge and your staff does not have the faintest idea how the handset was blacklisted. I am on the verge of losing out and it is because of MTN. I am having proof of purchase of the handset but MTN alleges i obtained it **********ly. This company is ******** people and no wonder it is fined all the time.