Soft brake paddle goes down 3.5 inches before firm. this is problem!!!
Then you should get this into the M-B dealer as soon as possible! A 2 year old vehicle should still be under warranty. Driving is optional, stopping is NOT!
The van may have air in the brake lines or the brake fluid may have overheated. Either way, the dealer can help, especially if you still meet the mileage requirements for your warranty.