Disappointed with service

Purchased a phone cover in January from the istore when I upgraded to the iPhone 7. I removed the cover two months ago only to find my phone seared with spot like scratches from the cover. I've been trying to get a hold of someone at the istore, but it is virtually impossible. Months have gone by and still no response. The back of my phone has scratches all over due to the abrasiveness of the materials used. I've paid close to R500 for this cover. Honestly, we pay a lot for apple products and expect a little more service from them. Their staffs level of service is pathetic. You cannot speak directly to any of them over the phone as they have a "Call Back Service". I am always traveling due to work and do not have time to be in and out of the istore.