I think you need to go freight, and you need to deal with the freight side of their business. Fedex ground is not Fedex freight. Sometimes that's not clear to people..
Same deal with UPS. UPS Ground is not UPS Freight.
I use to send drill parts to Canada and Visa Versa. Portal 2 portal, wasn't uncommon either. They drop off at the freight distribution warehouse, and you pick up at the freight distribution warehouse. Normally there is no loading fees as long as THEY can use a forklift..
The border crossing fees were always fuzzy, wording was really important. Made in Canada, being repaired in Canada, and being sold to the US all have different cost. Just like if your Returning a repaired pair of speakers vs Selling a pair of speakers.
Ask them what the cost is for a two way there and back? Cancel the way back, as an unused warranty option. There were a couple of legal (semi-honest) options. ;-)
Regards