How can I fix the broken boot lock of my VW Passat Estate?

The lock of the boot of my Passat estate has been playing up for a while. The lock/keyhole to open it manually is ceased up but I have been able to open and shut it with the sensor of the key. But sometimes the lever to open the boot is not working. I can hear the actual lock opening and closing but it seems the mechanical part that unhooks the boot doesn't seem to work. Problem is that the boot is closed now and I can't figure out how to take the lining of the bootdoor off to check the mechanical part. Any ideas?