Same thing happened to me last week. Forgot to add the red brake pads and called 1 day after order was placed. I was told once order is submitted and Vin issued changes are not possible.I was told that any changes after the VIN is assigned (which for me was next day after order) is very difficult and would require direct contact with the factory- and even then it may not be possible. No idea if that’s true. I changed my mind regarding the spoiler after I left the dealership but it was changed before the end of the day and the order accepted into the system.