Istore pre-Owned bunch of ****mers. Don’t buy from them

Istore pre owned sell faulty and damaged devices and lie to customers that the devices are certified pre-owned. I regret ever buying from istore pre owned and I don’t advise anyone to buy from them. I ordered an iphone XR in January as a gif for my lil sister who just matriculated and did well. Upon it’s arrival the phone screen was blank, not showing anything, I left on the charger overnight thinking maybe it’s the battery, but still nothing. I then sent an email to them telling them the phone is not working, they then organised a collection with courier, on the day of collecting the phone screen came ON, out of excitement I then immediately emailed them to stop the collection, of which they did. The phone then worked fine until the 12 of May. The screen went blank , I emailed them again because the phone was under warranty, the advised me to take the phone to any istore for assessment, I went istore in Mall of the North, whereby the technicians there told me they don’t deal with “PLG” devices but they will however book it in for repairs and I need to contact the istore preowned to let them know i booked my phone for repairs. Istore pre owned has a live chat which is USELESS, not helping. I later received a quotation of R10k to repair the screen because I apparently took the phone somewhere for repairs because they are picking third party display. How on earth is that possible?? How can I take the phone somewhere knowing it’s under warranty? They are actually ****ming people and I’m writing this with tears in my eyes because I worked hard for that money just be ****** like that? Honestly this is disgusting and I want my money back or a replacement device.