Insurance Rip-off

I took a contract phone with MTN and insured the phone. I submitted the claim on the 30Nov2019 and received feedback from the company on the 28th Dec after making numerous calls. My claim was declined due to not using the original sim card however I had phoned the insurance company to register the number that will be used and was assured it on the system and I'm covered. GuardRisk seems to be the insurance company that MTN is using. We are now in Feb and I'm still waiting even after I have advised that I called and they should listen to there recordings. My emails are now ignored I send emails and no response. I have paid insurance for 3months with no phone and I have to beg for even responses let alone what I have paid for , for months.