unhappy with istore service

I bought an iPad 8months ago, a week ago it just went off. I took it to istore in CanalWalk before I handed in the Technician tested it and couldn't boot up. He checked for marks and scratches and there were none. I believe those are the 1st line checks when handing in the device. He then confirmed that the device is still under warranty they don't fix ipads they replace them. I left then got a call that the iPad has pyra marks as if someone was trying to open it. I don't understand where are the marks coming from? why would I open the device knowing that it's still under warranty? I'm being sent from pillar to post for quotes that I should pay R8000 for an iPad I bought for R6000.

Please assist me I feel ****** and they are accusing me of opening the device. I'm not a technician.