Every case is different, but if this truly is a case of only 0.010" oversize I say fix it and move on.
Have you measured the part and had the manufacturer compare that to the drawing or the rest of the parts in the bin? Could be you have an oversize part, or an under size dash.
Whatever it is it's only 0.010", adjust it to fit.
Sorry, I didn't say who I worked for, and don't think it matters.
Not trying to give you a hard time, but it seems to me like you're being a little harsh on the vendor for a very minor issue with the original part (no comment on your later communications with them). If it were a whole 1/16" or an 1/8" I'd be on your side, but a few hairs is not much, I'd be happy that it will fit so well once you test fit and adjust prior to final assembly.
Grigg
