Bad bad service

Disappointed with the service. I bought a phone at pick n pay southgate 2022 december and 2024 jan the phone died and just becane black and no longet wants to switch on. I took it bacj to the store as it was still under warranty. They now phoned me and said i must pay 300 for checking the phone and i damaged the phone. The phone had a small screen crack and my othet phone as well is still working. They want to return the phpne to me and i must pay for them not having fixed it. They can keep the dead phone..i am not paying the 300.. bad bad service