Sorry I know you don't want to read this but was it your fault the clutch is worn/slipping or someone else who drives it? and what did you say to the garage that made them 'stonewall' you? after all 3000 miles is a lot of miles to take it back and say it is slipping. read on and you will better understand.
Clutch pedal 'riding' is a comon shortner of clutch life causing clutch wear sooner than expected. Using the pedal as a 'foot rest' and unconsciously depressing it and causing an undetectable slip of the driven plate resulting in shorter clutch life. If you think the garage is a reputable one then swallow your pride and return asking for a new clutch but all parts must be knew as you have heard it's alleged that there are pressure plates around that have been refurbished and passed as newly manufactured.
Just remember your garage has no control on how the clutch is used or abused. You could be in their position and I think you would think the same that after 3000 miles it's not your fault it's slipping it is the way you've used it. Ask around and you may or may not find somebody else who may have had trouble with this garage, other than that give them the benefit of the doubt or a wide berth the choice is yours.
bob
bob, October 2005