Mine does the same thing.
When i installed the chrome inner handles I had to take the card off and play with the rods inside. Nothing is bent, however after I put everything back together, it won't lock with the central heating. I can hear the motor inside the door starting and then giving up.
Had the same problem with my other car. The only reasonable solution came out to dismantle everything, remove the locking mechanism and the motor from the door and give it a good degreaser bath.
In other words, remove everything electrical, find a place where you can sink it entirely in degreaser (whatever you can find on your market). Then after it's been soaking for at least 30 minutes, using a tiny paintbrush simply try to clean all the dirt and crap until it becomes shiny bright again and all parts start moving easily.
Forget the graphite mess. It's good for pressure parts. Such as the window plastic moving parts (don't know how they are called). For the locking mechanism use normal engine oil (or sewing machine oil if you can find any as it's thinner).
That's it. Put everything back together and make sure u install it properly.
I haven;t done it yet as I need to find a garage for the day. It's not a good idea to leave the car open in Bulgaria for several hours outside the building
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However my biggest problem is that when the central locking locks the doors it doesn't lock the fuel cap. I have an aftermarket alarm, however I am 99% sure that it's been properly connected to the comfort module as the mechanic guy told me that he simply doesn't know where else to connect it if not the module.
So could it be the case that my problem with the driver door is failiing the fuel cap lock too.