Pay close attention to the belt tensioner pulley. I am told that they tend to wear out after 100,000 miles and will "fall apart after the belt tension is removed. You will then be stuck until you get more parts. If you are not sure hoe to change a serpentine belt, this may be a liitle too involved for you. If you look down on the belt and pulley, a worn tensioner pulley will be cocked over a little.
This info was provided by a tech at the local Mercedes dealer. I spoke to him after I picked up my car for the trap oxidizer recall. I have tha parts but have not installed yet. I would think another member could confirm the belt tensioner issue. Or wait till next week and I will confirm for you!