Hello and thankyou for using just answer. i suspect from what you have told me there are 2 areas i would be looking at 1st, the 1st area is when this symptom happens again do you loose the brake lights as well, if so i would suspect that the brake pedal switch is defective and this is shutting the throttle pedal down as it thinks you are putting your foot on brake pedal, the brake switch does 2 functions 1-operate the brake lights and 2-shut the throttle off, the 2nd area i would be looking at is the electronic throttle pedal and connections from throttle pedal through and up to throttle body, it may be advisable to change terminals at throttle pedal connector and at throttle body connector under bonnet, if this doesn't work then i would be looking to change the electronic throttle pedal complete, this is a non problem across the VW Group and they all use similar parts, just out of interest was there any fault codes stored when the skoda garage checked if so what were they, but if not then i would start at my 1st step and take it from there, hope this helps Chris

i would now check what i said as a next step this is poss the route of your issue, start from step 1 and see what you find, hope this helps Chris