ghost IMEI number

Istore pre-owned sold me a phone that has an IMEI number that is not recognised. I was shocked when my network provider confirmed that the IMEI number of the device that had been blocked on my request after being ****** did not match the one in the device box and invoice. I am now unable to claim insurance due to this *****ulent IMEI number issue, and getting hold of the store manager is a nightmare.