Are those Vibergs? If so, I can understand the reluctance to return them given how hard they are to source. Personally I would return them, however. It's not even a performance issue- they should not have been sold as firsts.
Any leads on navy on navy herringbones that are medium weight? This is for a sportcoat. Ideally it would be a medium sized bone and not so flimsy that it would be confused for an orphaned suit jacket. Something in a tight weaved shetland would be great.