All-Season Tires Issue for Delivery

I placed an order for a 2018 S560v4 last month for a December delivery. I ordered the 20" sports package wheels.
Today, after I decided to follow up with my order and ensure my delivery date on other details (including to make sure my wheels had M+S all season tires)...since I am in NYC and my car is 4matic.
I get a call saying that it is now impossible to get all season tires for 20" wheels and I should order the 19's. I have had 20" Mercedes wheels since I can remember and have always had all season from the dealer, including for my last delivery back in 2013, also in December.
Has anyone had experience or issues with this? I'm hoping its miscommunication and it can be resolved, but my sales person seemed very firm on this....I may even cancel the whole order If I cant get exactly what I want. Maybe it would just be better to purchase stateside....thoughts?



