I am assuming your system (judging by your listed car) used the analogue tuner, as analogue TV signals are no longer broadcast you need to find a digital tuner that can be plugged in to your COMAND.
Hi,
I have read in WIS that converting to Digital TV is just a matter of swapping the TV Tuner over to a Digital one.
Advantage of doing this is it still remains fully integrated into the car and no need for additional aerials etc.