As others have noted, dispute the charge with the credit card company and they'll take care of it. That's the reason that I use a credit card for every purchase, rather than a debit card. With a debit card you're just screwed.
Here's my two cents:
You never really know what you're getting into with an older tractor, especially with owner mods. If you're an A&P then you can probably handle it, but just a word of caution.
As others have noted, the N-tractors are under-powered compared to newer ones and lack a FEL or...