Time to find another parts house!!
I'm always going in looking for parts that aren't going on what they are supposed to fit. When they start asking about what the part came on, I may give them a list of vehicles the part may have come on, but usually start with 'this one of my Frankenstien projects', and they'll then usually sit back and see what I'm doing. Many times we end up getting 'the books' out.
I do find doing things like this, I probably spend more money on stuff that doesn't work, but that's not their problem, and your Vatozone guy is missing sales!!