Reading's probably a little too far out for you (and west!), but Berkshire Car Sounds did a very good job with mine. They were recommended to me by another owner (can't remember who, mind). When I've used them they've been rather busy, and have taken a week or so to be able to fit me in (which is probably a good sign anyway!), so I don't know if you'd have any luck for this weekend.

If they'd be of any use, I'll dig out their number for you.

Cheers,
Bryan.

Mark 2 #080000515
Was 12GB Blue, now 42GB Green!