Chris - happened to me this morning - I pulled up @ a building site to drop stuff off and couldn't open the door behind driver. Here we go I'm thinking - door jammed!
Co-incidentally I had to drive past dealers on the way back to office but just before I got there I thought I'd better check out the commands incase there was someting in there - low and behold - found it.
Apparently, while flicking through roof mounted command centre earlier on I somehow (inadvertantly) told the thing to only unlock drivers door first with remote.
So that one only took me 12000ks to find.
still learning........