I don't know how much you have into the instrument, but as you have the option to return it for a full refund, that's what I would advise and look for another horn. As I see it, that sort of casing damage is more serious than the bent slide, etc. Maybe it could be trued up with out a lot of difficulty. A repair tech could say. Unless it is a special instrument I would cut my losses before I had any. Rowuk's advice is sound. There are many instruments out there without that disabling problem. Good luck!