Promoteur increasing price after signing contract

[andrewc]

We are in dispute with our promoteur, who is trying to increase the price of our yet-to-be-built appartment, despite there being nothing in the Contrat de Reservation allowing him to do so.

We've had two legal opinions, both in our favour, but short of going to court (to be avoided) there doesn't seem to be any way of making the promoteur see sense.

Is there a French consumer protection / trading standards type organisation we could involve?

Thanks,
Andrew