Nope no option, weird, I’ve looked and can’t see anyway to update the software version, although it’s in a 2011 car so assumed it would have a postcode option as that is what I read.
The only thing that I could find was there was 2 versions of the RNS315. One which only did 4 digit postcode lookup and one which did the full 7. Nothing about it doing no lookup at all!!