KIA RIO BOOT

I have a KIA Rio Hatch Back 2016 Module and I bought it brand new in 2016 but now my boot is not opening and my Colleagues boot too who have the same car as mine and she only boot her car this year so that means that there's a Manufacture fault on the boots. So when I went to KIA Umhlanga I was advised that I have to pay R1000 and I refused because it's still under warranty plus I did not break the boot so they wanted to claim from my Maintenance Plan which also refused to pay and they decided that they will claim from my Warranty which refused to pay too.