"will/can I get support from Morgan"
As the dealer performed the labor, I would rate it unlikely to get contemporary Morgan to exert any sort of real pressure on their dealer, who is after all, an independent US company. (I say "contemporary Morgan" because they are no longer owned by the family, but rather a European conglomerate).
But rather than conjecture, why not contact Morgan and know what their stance is? But from a practical standpoint, you might make that your last resort, as you would likely be burning a bridge to your most local dealer.
I once had a somewhat similar dealer issue with a BMW I owned, and after repeated, email documented, attempts to get them to rectify the damage they caused to the car, I posted photos online on various venues and told the story of how they were ghosting me (after 6 cars purchased from them over 20 years). The new owner threatened to sue me, but I called his bluff, and we finally came to a cash settlement as I refused to have them correct the issue.
Or another perspective: As an attorney friend advised one time: "When you are in the right, pound the facts. When it's not so clear who is right, pound the table."
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