I'm being *****ed here really ??

On the 21st of September my wife's phone(Sumsung J5 pro) which i bought at Fnb digital planet, the phone screen started being turning blue from the bottom and the next 2 or 3 days later the whole screen went black, called Fnb told them about it they asked whether it fell or is it water damage told them niether they arrange for a courier to collect it on 27th told me that it take up 14 days so I've been calling them since the 14 days passed not getting anything from them, i called sure about three times trying to find out what's the hold up they told there's a quote and that the phone has physical abuse and that something cracked from the inside under the LCD display now the warranty ceased now i must pay for the repairs and the courier, now my question is the phone was complete and there was not even a scratch on the phone both the Digitizer and the back cover even the on side's how come the phone cracks inside while the shell had no sign of damage minding the fact that I'm still paying the phone until next year December now i must pay extra R1549.00 really dissatisfied by this