Mtn insurance dont pay claims

I lost my phone yesterday imfact it was ****** from my car, so i have insurance with mtn i sent all paperwork through i receive a call with a guy asking me questions i explain to him that my phone was charging in the car and i had 3 occupants in the car with me which one of them is my cousin i stop at the garage for some fuel and i quickly went into the shop (at the garage) leaving my phone in the car to get a red bull i didn't even take more than 5 minutes when i came back i drove off dropped them and continued to go to work i then realized on the highway about 30km from where i dropped the occupants that my phone is no longer there. So the representative of monitor insurance tells me that i was negligent to leave my phone unattended (in my own vehicle) so as a result they are declining my claim, so people if you are insured with mtn please be careful you are a victim of crime and mtn still have the nerve to tell you you're negligent.