Builder denies doing the work

I SOLD my French home and moved to a smaller one. The new owners then sued me, saying the veranda leaked, even though the contract said the property was sold "as is" with no guarantees.
The builder now denies doing the work. I asked an avocat to help, and was asked to find the builder’s invoice for the work and get witness statements (people attested to how they saw us paying him cash, which he insisted on, or working on the building).
The invoice lacked some details, such as his signature and Siret number, but had his name and letter heading. I have now lost the case and must pay for a new veranda and pay compensation to the builder, who said the invoice was not his.
The judge said my statements were not allowable as my avocat had not used the right forms. I am appealing, but could I go to Europe if I am unsuccessful?
It seems the "as is" clause carries no weight. I wonder if other readers have had similar problems with this, or with inadequate work by an avocat. L.S.

AVOCAT Gérard Barron said there was no recourse to the European Court in relation to private litigation, except in very exceptional circumstances, which do not include this case.

He added: "I am unable to comment on the claim that the lawyer made a mistake, but I will say that he started at a disadvantage to the extent that the reader seems to have accepted to deal with someone without checking whether he was properly registered (with a Siret number) and accepted to pay him cash. None of this would have happened if the matter had been wholly above board.

"Whether or not the ‘as is’ clause should have covered you, and whether or not it was a vice caché [a serious ‘hidden defect’ which the buyer could not have known about and the seller did not reveal], depends on the evidence. Were you or should you objectively have been aware that the veranda leaked or was likely to do so?

"If you loses on appeal, you might be able to make a case to the Cour de Cassation, on a point of law only, not on the facts, but you would have to pay."