Had a few issues with mine cutting out when the car was new, no problem for a long time. Maybe the dealer is aware and has updates he can carry out, worth a try. I see you are from Hampshire, I have had issues in the Southampton area on the M27.
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.