I'd say only drive to your tech and only if the shop is really close. Call MB roadside assistance and ask what they'll charge to fix it. The number should be on the inside of your glovebox door. Besides, you don't know where you'll be when the battery doesn't have enough juice to start the car. Beyond a certain depth of discharge a lead-acid battery will not recover.
Check the auto parts store for the kind of emercency belt that doesn't come as a closed loop. Seems like it's as much work to install such a belt as a real belt, though.