You've been ripped off, wardenc1ty. Sounds as if the seller has charged you for carriage but not paid the carrier, so you've paid carriage twice. Chase them up about it and, if that's the case, demand a refund of the cariage charge you paid them. If it turns out Fedex have made the mistake, much better. You can ask them for the higher sum to be repaid.
Just re-read the site in question to make sure you were not warned of any extra charges, first.