It is doubtful your problem is ECU, it will be the CEM. I'm sure if you were to replace it or even drop it into Vovo to have a quality diagnostic they would pin point the problem.
For what it cost you in loss of use, fuel, wear and tear, plus the fact it was the garages duty run around for the period (I bet they were laughing to themselves), as well as alternative transport and hassle - do you not think it would have been better all round and cheaper to have gone to Volvo in the first place??
So weeks later and great expense with absolutely nothing in the way of a fix? I would say very poor service from said garage?
Your symptoms are classic CEM problem which is a common fault, fair enough if a clean fixes it but if it doesn't then you need a new one. No point winging at the fact you've taken the car to a garage that doesn't know what they are doing, probably done little about it apart from use your car for the daily bacon butties run? Come on 350 miles???? WTF?
