Oh dear god, never, ever use Crawley Down!
I had a Renault Megane II before my Leon. Bought it from Renault UK in Croydon but took it to Crawley Down when it developed the first of many problems (google for the Parker's
Guide Forum thread on Megane IIs to find out how many there are
).
It had a (common) fault with the VVT system but despite several visits to their service department, CDG swore there was nothing wrong with it. I even gave them the Renault fault reference, as it had been published on Parker's by then.
Eventually I sacrificed a morning's holiday and took it back up to Croydon. They fixed it no
problem and new what the
problem was before they'd even driven it.
CDG also screwed me for labour for straightening a bent heatshield that was rubbing on the exhaust. That was also a known fault - they bend when you go through puddles as they weren't designed for right-hand-drive.
Let the monkeys at CDG touch my car? NEVER.