hi all at the mo my 2012 e class sat nav only works on a 6 figure postcode which is very random at times can you change the command system to take an 8 figure postcode.
OK, it sounds like you have the Audio-50-APS system, and that can't do it.
The COMAND (NTG4 with pcmcia card) in the E class (but not C class!!) can be updated with latest firmware and map to support it, but I don't think the Audio-50 APS can.
The COMAND (with SDcard slot) always supports 7 digit post-code.