Declined claim; on none valid reasons

Dissatisfied with my iPhone device insurance claim that has been declined by Santam. On the basis that the device was not being used with the MTN simcard (store where device was purchased) when device got damaged, outlining policy terms that I have never agreed to or signed for. Device has been paid off ; purchased/upgraded for above mentioned device October 2021-October 2023, and as 4th device upgrade/purchased at MTN. Contract ended for above mentioned device October 2023. Then proceeded, upgraded with another device, with first sim card number received at MTN. Contract currently active as device still being paid for. How can one make use of one simcard on two different devices?, on the iPhone that has been paid off and for current active contract device that is still being paid for?? The device is paid off, can make use of any simcard on the device as it is now regarded as my own property. Been consistently paying for insurance for the device, but device can now not be repaired or replaced.