Cellsure shying away from paying insured phone!!

Since about September 2013 I was using a Apple Iphone 5S. I renewed my contract online in 2013 and opted for this particular phone. Shortly after the renewal of the contract the phone was delivered to my home address<br> I was using this Iphone 5S for almost 22 months when I dropped it and the screen shattered. I took the phone to a Vodashop and was told that they will not repair the screen but will replace the phone. A private contractor quoted me R1600 to replace the screen. I was then informed by the lady in the Vodashop that Cellsure will only replace me a Iphone 4. I phoned cellsure about this and spoke to a very unaccommodating lady. She claimed I was only insured for a Iphone 4. She admitted that her system confirm that I was using an Iphone 5S and that I was using this phone from the time I had renewed my contract. She denied however that I got this phone as part of my upgrade.I asked to speak to a supervisor but was told to complain via e-mail. Cellsure does not reply!! <br> This phone was received as part of my upgrade and was accordingly insured yet Cellsure in what I perceive as deviousness does not live up to their obligation nor do they even respond to my complaint.