My thoughts on this: 1st: how long has it been since you changed your battery in your remote? I find that mine last about a year to two years before having to replace. 2nd: if you do not drive the car much you may have got the lube on the actuators hardened from lack of movement. Re-lubing or greasing them may do wonders. 3rd: how is the charge on the car battery? you may want to put a charger on it to bring it all the way up and see how things are before spending any real time on the problem.
When you use the car switch to open fuel or trunk do you get a click at the unit your trying to open, or is there just no sound except every once in a while. Same question with the remote.
Let us know and we can see if something else comes to mind.
good luck