I know I'll get stick for this, and frankly I deserve it. Someone gave me a 118,000 mile 2.2 turbo diesel civic (08 plate) with a slipping clutch. (In childish anger) I stuck it in 6th, 3000 revs, dropped clutch to spin without biting for 5 seconds. (It did smell a bit). Result - has not slipped again in 5000 miles. I suspect the problem (in my case) was something had contaminated the friction surfaces. Apart from those 5 seconds I never ride a clutch and I tend to do long journeys. This is no way to treat a car and I am ashamed to say I did it, but in my case it worked. If you're facing a £1000 bill, what's to lose?