We are having problems with the Stop Start that are becoming increasingly frequent - and dangerous!In the last three months there have been four occasions when either my wife or I have been through the following sequence of events:1/ Pull up at the stop line to enter a roundabout (we live near Milton Keynes, so there are lots of them!)2/ After a few seconds the 2.0TD engine cuts out (as it should) to save fuel3/ Take foot off brake. Engine restarts.4/ Press accelerator & move out onto roundabout.5/ After 5-10 yards the engine dies & the vehicle comes to a halt.6/ Put auto gearbox back into neutral & restart (as quickly as possible) waving apologies to other motorists!It is only a matter of time before this causes an accident. We have taken to disengaging the Stop-Start completely. But this should not happen.At this moment we are driving an A4 Avant courtesy car, having refused to take the fully serviced Q5 back after a service until / unless the Audi dealer sorts it out.The fact they cannot find it on their analyser is neither here not there. Nor is the fact they have driven to a few roundabouts and been unable to replicate this dangerous problem.