Free Traffic Legal Advice

so difficult to argue a loss as you're mobile and have use of a more convenient car for those journeys

yes but maybe not so convenient.
I would start putting pressure on the garage.
have they given you a copy of the bodyshop estimate/report?
have they told you EXACTLY what they are doing??

The nuclear option is not needed. I had call from the workshop manager saying they'd just got the car back from the bodyshop, fixed. I collected it this afternoon. Clearly I did right not to take the car when they were pressing me, and I guess they got fed up with a dented car in their yard and applied some pressure on th bodyshop.

With hindsight I should have been more pushy right at the start, then eased off if things seemed to be going well. It's much more difficult starting off easygoing then trying to harden up later on.

Just need to close it off with my insurance now there's no chance of any sort of claim arising.