How awful!
Some cheap things to try, if you haven't already, before you throw the new boots away:
1. Remove the insoles completely. If you want support, use paper (trace the original insoles on paper. Cut to match.), tape or moleskin on the bottom to provide support where needed. (BTW, raising the arch a bit MIGHT make your foot a little thinner - but it might just give you less space. Try both.)
2. Wear thinner socks (e.g., silk liner socks from a backpacking store). Better still, no socks, though that creates other issues.
3. Lace loosely at the bottom. Use an extra overhand cross to isolate the top and bottom. Better still, don't lace the bottom at all - start a few holes up.
If that combination, together with the toebox stretches you've already had done, isn't enough - I give up. Compensating for somewhat oversized boots is so much easier than somewhat undersized boots.
I'd say you've been more than fair to your dealer and skate tech. You haven't even told us all their names.
You trust the dealer enough to let them remount the blades on your old boots???
Even if Jackson wasn't helpful, I would let them know the dealer failed completely, that you are discussing your bad experience with Jackson boots over the Internet through this forum, and that you are switching boot brands. Probably won't help, but you don't know til you've tried.
BTW, Harlick has a pretty good reputation for dealing with wide toes, and for doing major boot customizations. But even for them - I'd call the manufacturer for a skate tech recommendation.
Good luck on your next new boots!