Finally had dealer confirmation of my order coming as an 85 and being built next week.
Funny how the dealer finally has answers on the day I get the response from my complaint to MB.
MB confirmed that existing agreement and issued PIN will be fine for accepting the 85 in place of the 80.
MB stated that following my complaint they approached Skoda UK and they have said that all dealers where notified of changes in October so there should have been no confusion.
At least everything is sorted now.