Phone customer services and complain, tell them your dealer is saying he knows nothing about the knuckle issue and needs educating. I assume your car isn't a 43.
2017 GLC AMG43 premium plus, night pack, leather, intel lights, 360 camera, side steps. = sadly gone
Now GLE450 Premium plus, Selenite, Black/White Nappa leather, Tech plus pack, Driving assistance pack, Tow pack, Off road pack, 22 inch wheels.