Power door locks.

I would first start by replacing the batteries in your remotes or try a different remote. Since this is not a vital function of the car, I would take my time figuring it out. Going to the repair shop and getting robbed is not fun.

But it doesnt lock when I manually click the lock button on the drivers side door

When you say it's an intermittent problem, I was thinking "relay" but there is none listed for your door locks. Okay, if it were a fuse problem, they burn out but do not come back to make an "intermittent" problem. But if you want to check for a loose fuse, it is #29 in the under dash fuse box, labeled "D/L-AM1"...it's 20 amps. Most likely it is the door switch that is worn, dirty or got wet. So if you want to lock your doors while driving, you can always click the door lock with the remote on the ignition key. That solution will not cost anything...