Insurance dispute

Good day. I need assistance please.The day I upgraded my contract with MTN I took out insurance on my device. For two years I did put in any claim,however after two years that contract was done and I upgraded again,I kept paying the insurance on the previous phone because I knew I would need it at a later stage, When my phone got damaged recently I tried to put in a claim just to fix the phone. The insurance company contacted me with all sorts of reasons as to why they can not fix my phone, I got fedup with them so I told them to cancel the insurance because it is of no benefit to me, now im still being billed and my line is now being suspended because im in arreas, why must I pay the insurance money if I cancelled it