Incorrect Device Blacklisted

I am unable to use my Iphone 6 which i received as an insurance claim from Finrite since the 26 Sep 2015 due to the fact that it will not pick up signal ,i even went to see my service provider who is Vodacom to have a sim swap processed but still my phone does not work ,after running from pillar to post it was eventually confirmed by Apple my device was blacklisted by Telkom Mobile although my phone & sim has no connection to Telkom after doing more research & visiting a Telkom Mobile store we found that Telkom wrote off contract # *** as bad debt & at the same time blacklisted the device connected to that number , for some reason they blacklisted my phones serial # instead of the phone connected to the number which is on contract with Telkom ,I immediately requested that my phone gets Unblacklisted as they can pick up on their system that my phone and number has no connection to them ,they refused to process the unblacklisting until i provide them with proof of purchase ,i contacted Finrite who furnished me with a signed letterhead confirming that the phone i have was issued to me by them ,Telkom has said the letterhead is not good enough as POP & now wont unblacklist