Item Returned in mind cond..now you say Manhandled

Bought a Mobicell tablet, after 21 days of having this tablet, it switched off when I tried to charge it, the device switches on and off continuously. Returned to Cell C Boksburg and was sent in for a repair. Then received a message advising me to pay R1100. My husband called and he was advised that the mother board has gone on the device. He later was advised that the LED screen needs to be repaired due to man handling. When I booked the device in there was no scratches no marks on the device. How the hell is this possible. This device has a 2 year Warranty and this should be covered by this. If it was man handled this was done in transit. I have all the documents proving the device was in good condition. Cell C Boksburg have not been able to receive full details of the damages either. If there are two stories then someone is hiding something. I expect the tablet to be replaced under warranty. Called repair centre today who advised that the person dealing with it is not in. A few minutes later it will now be sent to the supervisor. I hope that this complaint will ensure that this gets dealt with properly.