this is a copy of my letter to the main dealer supplier, it tells all.

I purchased the car primarily to tow my new caravan on holidays. We have two other cars we use for day-to-day use. a Mercedes sport and a Jeep Grand Cherokee, whilst they are both very old, they are ideal for local use. In Three years in the Audi Q7 we have covered just 53,000kms, mostly in the summer months whilst traveling on holidays.
At three months of owning the car, we travelled to Germany to collect the new caravan, we had not yet reached Alicante when we suffered a complete loss of all functions and power, whist traveling at 100kph on the autoroute. this loss lasted just 2 seconds and then all resumed. We were extremely worried and concerned, as a major accident could have happened with a lorry crashing into the rear of us, we telephoned immediately and spoke with Pilar, who suggested we continue and if it happened again to go to an Audi garage, and if not to bring it back to Audi Marbella for a check. on the way back from Germany we holidayed in France and once again, some one month later on our return to Spain, it happened again.
We took the car to you and you put the car onto your computer where nothing showed up as a fault and worse still the computer had not recorded anything!

We have now suffered this loss 7 times and each time your computer has not shown any fault. it seems as though the computer is not programmed very well!

Early december 2010 we suffered this loss again and i took the car immediately to you. in mid January 2011 i called to collect the car, but once again no fix had been made. i asked you for a more thorough check and you tested the Injectors which all reported good.

On Friday the 4th February the entire electronic system went haywire resulting in a complete loss of control. i very slowly drove the car to you as it was intermittently losing controls.
1. the drive letters PRNDS are all lit up. normally it is only the drive you have selected.
2. a warning "ADAPTIVE LIGHT DEFECTIVE"
3. a warning "HEADLIGHT RANGE CONTROL DEFECTIVE"
4. the picture of a car with zig zag under it is alight.
5. a warning "AUDI HILL HOLD IS DEFECTIVE"
6. The wipers keep operating
7. loss of control with steering whilst going around a corner
8. door locks continuously locking and unlocking.
9. a warning "ESP FAULT"
10. the lights around the heater controls flashing on and off.
11. warning "ADAPTIVE AIR SUSPENSION"
12. a symbol of a lamp with lines alongside and an arrow. see drawing
13. a symbol of a car sideways on with an arrow going upwards is alight.
14. the car door locking with the remote control will not function

perhaps these are all connected to the car losing all power whilst driving?
Perhaps the ECU needs renewing?
You have reported that over the past seven days the vehicle has continuously shown either no faults or all these faults and more.
As i stated at the beginning, i will not risk my life or my families and drive this car until you find and fix the very dangerous fault.
Alternatively, please refund all monies paid or supply another car.

 

Received back today, all seems well.
they have exchanged the main computer and a "starter" computer.
garage very helpful and polite, we hope for the best.