Just got back from a 3,284 km round trip delivering 4 dogs north, south, east, and west so apologies to all for the late reply.
Firstly, I am most impressed with the level of technical knowledge on here, I don't pretend to understand every point made but it all adds to understanding and I am most grateful for the input.
As regards a CoC or IVA certificate, I haven't had either. All I got was a receipted invoice when I collected it. No confirmation order and therefore no chassis number. There is a VIN plate on the chassis so I suppose the number is stamped there but it isn't here at the moment so can't check. It is still down in Perigueux which is 50 kms away. Next time I'm down there I'll check but I know the caravan was completed on the day it was collected, April the 22nd, because I stood there watching them finishing it. However, I don't know when the chassis was made but within a few days I would have thought as putting together the 2 halves of the body and fixing them to the chassis wouldn't be more than a day's work. There was another chassis under construction on a table nearby, maybe yours Phil, I wish I had paid more attention to it now in the light of what has happened.
After a silence of more than a week there was another email from AVI yesterday to say that they are an honourable company (in answer to my suspicion that they want to destroy the evidence) and will fulfill their obligations to replace the chassis with another once they get the original back. They don't answer the specific point as to why they want to spend over 5,000 quid more than my local solution would cost them.
My way is clear now I think. First I will ask the insurers today if their legal department has got anywhere and has any advice. If not, I will write to AVI and give them 2 weeks to agree to pay for the local chassis and my expenses to date, around €1,800 in total. Failing that I will get the work done here anyway and sue them for the money via the courts in England. County Court first, hopefully a favourable judgement, if they don't pay Send in The Sheriffs. I should point out for our American friends that this is an ancient post in England, they are the enforcement arm of the High Court here and they go in with a van, force entry if necessary, and take away computers and anything else of value in order to pay me.
At the very worst I will be 1,500 quid down but at least will have my Teardrop back on a reliable chassis, and within a couple of weeks. It has been extra work this week doing without it.