For starters, as was mentioned multiple times: call MB immediately and let them sort it out.
Fact of the matter is, what you’re describing is indeed illegal. Not “naughty” but actually illegal – it’s a bait and switch attempt.
You ordered the Ultimate, the Ultimate is still available to order, is still on the scheme etc pp – that’s what you signed for, including an agreed price with Vauxhall.
That’s it, there’s nothing else. They can’t tell you “well here’s a lower spec for more money”, it’s not how it works. The fact that they immediately asked for the AP to be paid at order already would’ve made me reconsider, that already seems crooked to me. As, again, was mentioned before, you don’t pay a deposit on AP. You do pay a deposit on additional extras if you order them, either in full, or like we did, 50% of it.
As much as it sucks, i’d reject it and tell them to suck a bag of di..nky potatoes.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.