When I bought my E89 it was wrongly described as having DAB and so I went back to BMW to ask them to rectify it. There were three options
A dab unit which has a small remote control and they put a DAB aerial into the front windscreen. My husband has this on his 3 series, but I didn't like it as the aerial spoilt the clear windscreen and the remote is too small for me to work without reading glasses (not great while driving)
There were other cheaper plug and play receivers, but these all had to be powered from the cigarette lighter which meant having the ash tray open all the time.
The final option was great potentially as there is a firm in Surrey who will completely retrofit a BMW dab into your car and put the aerial concealed as if was factory fitted.
This option would have been perfect for me, but my car is my daily and I wasn't prepared to lose it for a week and BMW muttered something about invalidating warranty as a third party would have been involved.
So I took financial compensation instead. If you car isn't your daily and you want to see more about the option, I can look up the email link BMW sent to me at the time.
I do miss aspects of my dab radio, but not enough that I want to clutter up the lovely clean look of the cabin and windscreen.
Viv