Mokka won't start after a stall

My 68 plate Mokka 1.4 petrol has a random issue which I hope someone help with.....
Having always had a 1.6 or bigger engine I find that the Mokka is somewhat more prone to stalling if not given enough revs on hill starts or in hurried drive-offs.
However, the stalling isn't the problem; it's that sometimes after a stall, the engine cannot be restarted - as if the clutch isn't depressed. It doesn't happen often but typically always with an impatient queue behind. It's only happened about eight times in the 6 months I've had it, less so now as I'm now careful to over-rev but I still get caught out.
I can't say I've noticed if it happens after the auto-stop-start has attempted (and failed) or had an immediate re-stall.
I initially tried removing/reinserting the key, pressing pedals etc but it wouldn't start.
I read on a forum somewhere about some electrical circuits remaining active after the ignition's turned off and only going off when the driver's door is opened so in desperation I tried that and on the twice I tried it, I was able to restart manually straight away.
I'm beginning to think it could be something to do with the auto-stop-start; as if it's "getting confused".
I had it into the dealership and got the usual chocolate fireguard response and of course if the fault isn't apparent they can't fix it.
Has anyone any knowledge of this or similar effects that I can use to argue my case?
Davy