If I fail to start my car every day it has to be jumped off. I have a new battery. If I forget to start it even 1 day it won’t staart!!
you might have something staying on. check to see if any lights are staying on. like glovebox light, under hood light, trunk light. check at night to make sure your brake lights are not sticking on. if none of those are on then you have a parasitic drain somewhere.
Charging system is ok?
What model and year Mercedes Benz? Is it in warranty? If so, the dealer might find a parasitic electrical draw that MB will pay to fix. If it’s not in warranty, a good shop could find the problem and solve it. Just be aware that it could take time to find it. You will be without the car and the shop will charge you to fix it. These things aren’t always easy to find, and it could be expensive.
This has some good suggestions for things to check,