On 10-27-22 the van was parked in my home driveway where it had been parked overnight. The engine was running for approximately 10 minutes while loading things into the vehicle. The vehicle was in park and the hand parking brake was not engaged. Prior to leaving I noticed the dash icon showing the rear door was not fully shut and went back to close it. Once I closed the rear door it then appeared that the transmission shifted itself into neutral and the van rolled back into the garage while I was standing outside of it. I have home surveillance camera footage showing the incident as it happened. I have tried to convey this information to Mercedes Benz but interactions with them have been less than helpful.