You should use MB antifreeze, Zerox G-05, which meets the MB spec, or Dexcool, which doesn't meet the MB spec, but accomplishes the same goal. Conventional green antifreeze is loaded with silicates an other inorganic salts that will clog up the radiator tubes and shorten pump seal life due to the abrasive nature of the additives.
Conventional green antifreeze belongs in the list of obsolete service products along with alcohol based antifreeze and non-detergent oil.
Suggest you also find another shop or in the future specifiy or supply the maintenance products you want used. If they aren't smart enough to use readily available Zerex G-05 instead of the green stuff, I have to question their competence to service M-B automobiles.