I quite Agree far to complex, great whilst they work, Hired a few Astra Twin Tops whilst holidaying, amazing roof mechanism but boy is that just heart ache to own, and quite intersetingly enough I have had a few stand offs with hire companies abroad over the Astra TT as they never seem to have enough of them, the reason they spend a lot of time in the garage having a roof repair so you end up waiting for sometimes up to an hour for the next one in and this is quite regular, hire a Renault or Pug CC fine but they are more expensive to hire but seem to stand up to the hire car market bashing better than the Astra, not that this paragraph means much to you but it just shows the more complex the roof it the more it "breaks"
The dealer may try to argue the point that the vehicle was fit for purpose at the time he released it to you, you must have operated the roof incorectly and will possibly go along the lines of the roof is a specalist area and he does not have a speaclist on site, etc, etc,you know the schpeel, if he is a renowed dealer then perhaps the presure of the Consumer people and the threat of publicity might be enough to get him moving on it, you will possably have to prove he knew the roof was a problem, it can be quite a grey area, but maybe the bigest gun you have is publicity, esprcially in todays climate where buying cars is very thin on the ground at present.
You may find that the fear of this roof for the dealer is making him deny everything now, it could have "just" happened perhaps with him it may be a bit slow on retracting, but him not being a Renault dealer has not thought about it, as far as he is concered the roof works fine, I nearly bought one where the parcel shelf sat ontop of the boot, the dealer thought that was where it sat! really did not realise it was wrong, when I pointed it out he looked quite suprised and then said it does make some odd noises sometimes when closing, he withdrew it from sale.
As said you may find him hard to deal with as there is not enough profit in the car to repair the roof if it has to go to Renault if you can see what I mean, as he probally will not be able to repair this roof for you.
Does it not run from a small motor on the driver side. you must be able to see all the mechanics now under the shelf can you not see what is causing it to jam?
This is one of the reasons why we just trade em on, we sell Audi, VW, Mazda, Seat, Suzuki and Mitsu but we still strade on the Renaults, Pugs, Vauxhalls Etc with the electic roofs as we would not have a clue if it went wrong, and would cost us dearly.
The Renault roof is based on the Merc roof by the way if you did not know, perhaps a merc tec could help if you knew one.
Hope all goes well for you they are a real pain when they break, sorry to hear your misfortune with a car dealer, but also try to understand there is not as much profit in used cars as people usually think, not that I am protecting him, I don't know him so he will be worying about cost as well. Publicty is a great tool though!