Originally Posted by rmw04c
How would I convince them to do that, considering they denied that it was even possible in the first place??
It seems to me that the production date of your 335is is prior to 03/11 -the 6NF option is the telltale.
The dealer will be unable to retrofit the 6NR, however contact forum vendor BimmerTech for details. He can retrofit the 6NR in your car -it has the required main hardware to allow it.