Sat-Nav starts navigating from Gemany when I am in UK?

I have Mercedes E320 CDi on 2005/6 with Command. When I enter a UK post code or start navigation, my journey starts from Germany and starts navigating from there. Would an updatted disc fix this or is there anyway I can re-set. Battery had gone flat and recharged. Have already re-set all data on the Command to show car is in UK. (country Settings). Any idea anyone?