I’m with Alex, that’s nearing “pull your pants down” time. Walk away, get at least 2 other quotes. Research locally, perhaps try a social media site such as Nextdoor and ask for mechanic/garage recommendations. Make sure you specify recommendations from personal experience, not brother Joes best mate. You maybe pleasantly surprised.
Just a thought, is this work because of an MOT failure or the garage taking the proverbial?
Good luck with it.