Never had a problem adding extra’s.
I doub’t Mb have advised dealers its customers can not add optional extra’s. (A) its paid for by the customer (B) the resale value will be higher -we all know how much Mb like their money!
I was in Nissan last Thursday and was advised I could add fog lights to the QQ Tecna trim, but I would have to pay this up front £170 from memory. I’m going back Wednesday to test drive the QQ and X trail.
Its like Mb the dealer saying you can’t pay to have optional mats!
The only possible escuse is its adding extra delivery time, dependant on what extra and Mb don’t want that, but you would think after 3 months Mb would have put a bulliton out to its customers saying so.
Try ringing a dealer in the next county or so.