Different IMEI numbers from device and in the box

I had a replacement device Huawei Y5 with IMEI number *** from my insurance'a suplier Celullucity Mobile which had a different IMEI number from the one that was in the box ***,aftwr I discovered the difference of the IMEI numbers I decided to keep the correct one from the phone safe, on the 30th of April 2019 I lost my Huawei in a car accident in Pretoria, when I reported the device from the network provider MTN using the divice that was in the box *4465 I was told by MTN that the IMEI number 4465 doesn't link with my device and my cellphone number ***, and I provided them with the one I got from the phone before I lost it which is *5363 and it was confirmed to be the correct one with the following call reference numbers ***,***,***, ***,***,***.... I was then provided the Itc number which is with my insurance number, but the insurance is now refusing to replace my device because on their system they have a different IMEI number which is the incorrect one that was in the box not what was in the phone despite all the confirmations provided by MTN that the correct IMEI number is the one ending with 5363 and the one ending with 4465 belongs to someone else who's a vodacom user and that was the information provided and confirmed by the supplier Celullucity Mobile and this suplier is as well withholding this information instead of giving this information about the different IMEI numbers to the insurance so that I can get a new device. I have been sent from pilar to post by the insurance company and their suplier from April up until now, they keep saying I muat get the ITC number using the IMEI number which ends with 4465 while MTN confirmed that they can't provide my the Itc number using someone's else's IMEI number because they'll be blocking someone else's cellphone which I think the problem started from where the phone was packaged in a wrong box because it was delivered to me sealed while the insurance only quoted the IMEI number that was in the box while the correct one was in the sealed device.