Sorry, no solution, but I'm experiencing exactly the same with my car, Clio 3 2006. I have reported it to the agent, with the same comment, they could also not see anything in the car's event logs. In fear of them causing more damage to the vehicle, I instructed them to rather leave it and I will live with it.
I have however experience something very frightning in this vehicle on the 13th of July 2008. I was returning from holiday and stop to re-fuel. Pulling away from the petrol station, it was quite uphill and I tried to accellerate quickly to join the on coming highway traffic. When I went from 3rd to 4th, the engine RPM suddenly shot up to maximum rpm (+/- 6500 rpm.)
I tried to pull the accelerator pedal up by hand, but that was already in the up (Idle) position. Then the road start to flatten out and the vehicle kept on accelerating, I tried to cut the engine with the Start/Stop Button, with no success. Everytime I push the clutch pedal, the engine just went back to Max RPM and I was afraid of damaging the engine.
By this time I was already doing about 160Km/h. I then inserted the card into the emergency slot and at the 3rd attempt with the start/stop button, I could get the engine to cut.
I pulled off and re-started the engine, which just went straight back to maximum RPM, I could however get it to cut immediately this time.
On opening the drivers door, the electrical power normally cuts completely, I then attempted another start and everything was normal. I completed my journey, +/- 250Km with no problems.
I'm now very concerned about this, if this would have happened in peak hour traffic, I would have definitely crashed the vehicle and I'm now driving with a constant fear that it can happen again. I have reported the incident to my dealer, they have requested me to monitor the vehicle for the next couple of days.
Nick, July 2008