I'm sure they'd understand that people order lots of parts for a restoration long before they're ever installed. I'd at least attempt talking to them on the phone. If they made a mistake in the manufacturing process that renders the product unusable, it shouldn't matter how long it's been.
They should also understand that you attempted to rectify the problem yourself so as not to trouble them with it. You haven't ruined anything - the bolts are nothing.
Worth a try.
