Clutch Problem Or Software Glitch?

[Guest jascha]

I have 05/55 C5 138 VTR Turbo Diesel saloon with 23,000 miles covered. I tow a caravan, and specifically bought the car for this purpose and have generally had great service from the car. Last summer as I was towing up through France at grain harvest time, the car came into contact with a cloud of cereal dust which brought the anti pollutant warning screaming into action and a big loss of power (turbo not working etc). I managed to limp about twenty kms to a main dealer....described the cause of the problem, linked up to the ECU for a full diagnostic, and you've guessed it, nothing came up! In fact, after five start/stop cycles the car seemed to have sorted itself out, and we were able to proceed to our evening destination. The very next morning, all seemed OK; we had been under way for about five minutes when the engine revved free in fifth gear, up from about 2000 revs, and then sorted itself out. It did this once again on the journey and then not until some months later when I was solo and we had a recurrence. It lasts very briefly and may now happen in 3rd/4th/5th gear, however, it could be problemmatic if I was overtaking uphill? It doesn't happen on every trip; I've just been on caravan holiday in the SW and most journeys covered were free from trouble. Last Autumn the car was serviced by Bedford Citroen authorised service centre. I told them of the problem, and again nothing showed up. They tested the clutch and pronounced it OK. Has anybody else reported the problem? Do you think the two things as described are related in any way? Could it be a software problem? I am aware that this machine boasts a lot of cutting edge technical gizmos and hope against hope that there might be a logical explanation......!