I had the most ghastly experience with a Free Now job on Friday. I phoned the client and, while I was clearly in the wrong place, I just couldn't get enough comprehensible words out of him to resolve the issue so I tried to cancel the job. Whichever reason I selected (I tried them all) just opened an alert with some nonsense about the inconvenience of cancelling and two options - an X to close the dialogue and a "Continue Driving" button which also closed the alert. Neither would actually cancel the job so I had to enter a fare of €3.80 and send them a strongly worded message via the job specific help button which I accessed by selecting the "View Previous Layout" option in the Earnings section.
As Octy suggests the engine would be racing if the clutch was slipping, erm.... or the car would sound like a tractor if the Dual Mass Flywheel was faulty. If you are buying a clutch, best to go the Euroclutch in Baldoyle. He done my old MKII Octy at 150,494 kilos and it's still going strong with c.340,000 kilos on the clock. If you've got a DMF don't get a cheap solid conversion unless the car's on it's last legs e.g. within c.100,000 kilos of end of service.
Anywaysanall, with them DCIs I'd be looking at the boost pressure control valve and the vaccuum hoses connected to it (check for leaks) and the EGR valve and any pipes connected to it (clean thoroughly inside and out). If turning it off and on again temporarily solves the issue you could be looking at the accelerator's potentiometer.