Sent broken computer to repair company, they replaced it with a different defective laptop after 2.5 months - what should I do and where do I stand? (ENGLAND)

Around mid-January, the main USB-C/charging port for my laptop (purchased May 2023) died. Luckily, it had a back-up port which I was able to use to back up my whole computer, and I sent it off under extended warranty to be repaired.

After a two-and-a-half month long saga, they finally returned a laptop to me on 04/04/2026. A replacement, second-hand laptop, which has a screen defect (looks like purplish-blue burn-in at the top left-hand corner of the screen), as well as overheating very quickly while in sleep mode or running zero programs.

Some very cursory digging shows that this laptop was purchased for cheap from eBay (the original value of the laptop was around £2000, the one on eBay was bought for about £850) and while the description for the eBay listing doesn't mention the burn-in, the first photo of it shows it very clearly. I feel like they bought the laptop, opened the box to check everything was there, then just sent it to me without even turning it on, as the burn-in can be seen as soon as the laptop is started up.

What would be my best course of action to get this rectified? I am currently drafting an email to them which has a timeline of all communication from them (including being told at the start of March that they had "ordered parts" and there had been a delay sourcing them, followed by a "parts ordered" email at the end of March which matches the purchase date of the eBay laptop). I am also sending photos of the replacement laptop, as well as a link to the eBay listing, showing that they are the same laptop.

Would it be within my rights to request that they either replace mine with a brand-new one, or that they fully repair my old one? I understand that electronics depreciate in value, but given the fact that the replacement they gave me has a different defect, I can't trust that they will actually find a properly functioning second-hand device. The laptop is a touchscreen gaming laptop, so it's a lot harder to replace like-for-like without actually spending out.

Thank you for any help you can offer.