Dell continually failing to repair faulty system

Dell UK have had an open fault on my PC for months, I have had 3 on site repairs, 1 return to workshop, plus remote reconfiguration attempts, the system still reboots on an almost daily basis logging a 153 GPU error (problem associated with the Nvidia GPU

My warranty runs out this week so am unsure whether Dell will fix this or just wait till the end of warranty and ignore the problem.

How to I get this escallated and the system replaced, it is obvious that after multiple attempts they cannot fix the issue and there a fundamental problem.

I keep getting told that this is escalated, not hearing anything until I call in again and then getting the same software fix that does not work. Would like this issue be taken seriously by Dell and the problems with the system resolved