I would hope that the shop gave you a 'loaner' vehicle for the duration, without charge or mileage restrictions. Your problem is unique, your V70 is completely covered by the factory.
Your only recourse is to ask them to replace the V70 if they cannot find a 'cure' in a reasonable time, less than 6 weeks.

I am surprised that you could start the engine when all of the electrics are still off and not functioning. To me, that indicates at least 2 computer modules have failed - the security and instrument computers. The likelyhood of both of them going off line is quite rare.

Have you visited:

http://www.volvoforums.org.uk/

They might be in a better position to help than us, we are not allowed to buy D5 versions of Volvos.

Klaus
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There is no present time, just the past and future