Does it do it if you keep your foot on the clutch or brake pedal, it shouldnt stop unless its in neutral and all feet off the pedals and no heavy engine demand from the electrical systems you might have on, and engine up to temperature of course?
Does it do it if the air conditioning is on? It shouldnt, due to the demand on the engine, though maybe you dont have that on the D One as standard, its a no cost option when ordering the car for some reason, so daft not to have it really?
If you keep the air con on if you have it, that should cut out the stop start too?
Are the idle revs a little too slow? I know when learning you tell pupils to crawl up to a corner and try to keep going and pull out if nothing is coming without stopping, this can drag the engine revs right down so if you suddenly declutch to stop, the car might think is its about to stall and this might affect the stop start system?
Does it do it every time you stop? or only in certain cases?