New clutch fitted

I have just had a new clutch and dual mass flywheel fitted and there is no pressure in the pedal once the car is idle for long periods. I have to pump the pedal for about a minute to build up the pressure and it's fine while I'm driving. Took the car back to the garage and the mechanic said it needed time to bed in and also bled it but said he only got a little air out of it. The next day, the exact same happened. It's going back to the garage on Monday to do some fault finding, but I'm beginning to think it needs a thorough bleed or there's a potential leak somewhere.



Has anyone else experienced the same problem?