Def 90 - SE London / N Kent - Clutch Repair Recommendations?

Hi

First post on here.

Ive got a 2007 Def 90 - clutch was rattling away at idle, now the gears have started crunching on change. My local main dealer quoted > £800 to replace the clutch at the last service.

Can anyone recommend a garage who'll do a good job on it anywhere in SE London / N Kent area?

Thanks!

Chris