Sounds to me like your electronic throttle actuator or associated electronics is bad, which is a common problem on these cars.

I would have this tested by a dealer.

What were the codes that the dealer pulled from your car's computer? This would help in diagnosing the problem, very likely.

Where is Switzerland are you located? We have a couple of members over on 500ecstasy.com who are located there, and one or two in Northern Italy.

Regards,
Gerry