The seller is a crook and sold you "damamged" goods knowingly. No way is it meant to be free floating. Look at all the images I supplied.

BUT unless the barrel is bent, I doubt it is a big repair. As said I would have a look at the big barrel wedge to see if it is putting too much pressure on the top barrel.

A good competent DR gunsmith will be able to advise you. And "re-fixing" at the muzzle as required.

Good names are mentioned on the forums. Do search on the double rifle forum for "Gunsmith". I will also start off new threads as a resource. People here can advise three US based names.

Give the seller a bad review if on a auction site.