Insured and Paying! No cover from MTN

A few months ago I was upgraded and received a Sony Z3. It slipped out of my pocket getting out the car and shattered. I returned to fill in a claim form at Hyde Park MTN. They informed me that I did not ask for insurance. I have been with MTN for 15 years and always insured. I'm insured on the system currently and I am being charged and paying insurance. The store manager confirmed in front of me that I am insured on their system and that there must be some mistake. Upon Contract upgrade the sales rep asked me if I am insured and I rep**** yes, with MTN. He then advised me not to re apply as I am already insured with them the insurance would be carried over. My policy is clearly active on their system. MTN continues to reject my claims, even though they charge me insurance and I pay insurance on my contract monthly. I have been using my old sony Z1 since, that's has now been ****** last week. I now have no phone and no answer from MTN!! I have contacted regional managers and still no resolution. HOW CAN MTN BE ALLOWED TO GET AWAY WITH THIS *******?