Have to agree tha this really does sound like a clutch release thrust bearing problem. If your garage did NOT replace it with the clutch then they've stupidly tried to save a few quid and caused much more trouble. It is worrying that they had to re-do the job as they'd done it wrong first time around - a clutch replacement is hardly rocket science or brain surgery, is it ? Maybe they have put the release bearing in the wrong way around, or managed to introduce dirt into the equation. If you are in the RAC or AA then I would suggest you let one of their experts check over the workmanship .