renault laguna computer prob.

I was driving along when I heard a beep and the rev counter, speedo and heater gauge died and the display said airbag and handbrake check. Took it straight to renault dealership who said it was a problem with computer. When you switch the car off it can notbe restarted again for 10 mins after which it has reset and fine. Does anyone know who the best person is to write to with a complaint to renault. As I have had no joy with the dealership although the car is still within its warranty and has done only 12,000 miles. I was offered a van as a courtesy car but didnot have my licence or wallet wih me and was told the office shuts in ten mins so my choice of transport home was to walk!!!!!!!!