Insurance decline due to their system not functioning properly.

I have been an MTN client for years now and I have been paying the devices and insurance for 1 of the phones on a timely basis. I loose my phone and they tell me that my claim has been declined as their systems do not show that the number was active in the device at the time of loss, my Sim card got lost with the device so I don't know whether I am now being punished because their systems are not working properly. Im actually very disturbed and disappointed at the moment but I will definitely dispute this outcome.