complaint about the repairing of my phone.

I bought my phone at Markhams store in Green Acres on the 6 October 2014. in the mid of March 2015 my phone just shut down, it did not want to switch on. then i returned the phone to a Markhams store in Gugulethu mall. There i was told my phone will be taken to the MTN repair centre, and I did inform the lady whom was serving me that my phone is still under 6-12 months warranty and I do have an insurance. on the 1st May 2015 my mother recieved an sms informing her that if I need to pay R1500 for the repairing of the phone, and the phone was either dropped on the floor or it fell in the water. I then told my mother that my phone has never fell into water nor has it been dropped and if i damaged the phone i was going to take it to the repair centre myself and not report it to the stall. The MTN consultant contacted my mother, asking if will i pay for the phone and my mother made it clear that why doesn't the insurance cover for the phone as it is under insurance.