CLAIM REJECTED OVER SIM CARD.

I lost my tablet and made a claim with MTN insurance. The claim was rejected by their underwriter GAURDRISK on the basis that I was using a wrong sim card.Yet I was using the insured sim card even when I lost the tablet. Now I have been trying to communicate with them to object the rejection I cannot reach them. MTN insurance does not answer call you spen the whole day holdingand they dont respond to emails. GAURDRISK their emails dont go through and their phone number go to voicemail or they ring and are not answered. Is Gaurdrisk a company that exists? The only reaponse I got was from a guy called mike from MTN who said their dept will get through to me .but its been a week now nothing has happened. I wads ****** in daylight because I want them to clarify as to which number they claimed. I was using. There is no one to communicate with in both companies. MTN quickly deacivated my policy with them after rejectin me. If there is any one from noth companies who can give me an answer I would be grateful