Re: Exchange issue
From your invoice, it's very clear what you ordered. From what you say you received, it's very clear that you didn't receive what you ordered. It sounds like they don't want to send you what you ordered, but instead want to send you something else.
Definitely time to go up to the next level (at least that is what I would do) as it sounds like a huge communication issue (or just a basic mis-understanding on their part of what the problem actually is.)
1972 Chevelle SS Clone, 454, 200-4r, 3.08
1981 Camaro Z28, 355, TH350, 3.73