URGENT: Vacuum lock for fuel filler door

[kiato4]

Hey all:
I went to fill up yesterday when I couldn't open my fuel filler door. I had to go in the trunk and manually pull on the actuator to open it. It was a cold day so I thought maybe it froze, so I locked and unlocked the car a couple of times but still nothing. The other thing I noticed is that I can no longer lock the whole car from the passenger front door, if I lock that door it only locks that one and the vacuum system won't even turn on. What does this mean? Is that a vacuum leak or a bad actuator? Please give me some ideas because it is a pain to reach in the trunk everytime I have to fill up. Just to clarify, everything else works as it should. All doors lock when the drivers door is locked. The trunk never locked or unlocked the whole car for me. There is a way to deactivate it and I think it was deactivated (the procedure is in the manual...it's fine as it is for me).
Thanks in advance.