Manual Door Locks completely stuck

I have a Sunfire 2002 coupe with manual door locks, and they are almost completely impossible to unlock with the key. Yes, it is freezing friggin cold here (5 degrees today) but I wonder if there is some way to make these things work better, they are super sticky even in warmer temps. The shop I had the oil changed at sprayed some wd40 type oil in there and it seems worse now. I want to get the locks converted to power but I want to be able to lock my car and unlock it in the meantime. I am wondering if I have to take the doors apart and if so how is that accomplished?
Thanks,
undivine

The WD40 should have loosened then up.Did the shop actually spray into the lock with a red tube on the can of WD40?If the problem isn't there,then it's probally in the latch assembly.Take off your door panels(there are threads on here already about this).Spray down your latch assembly with some oil.Also spray inside your latch assembly.This should fix it up.