Alright mate, had same problem with passsenger side window and the window regulator needs replacing. I had a 'sticky' sound to the window everytime I put it down and then one day it just stuck and didn't go back up again. I thought it might have come off the runners too but after taking a closer look it was the window regulator.
Got hold of an aftermarket unit under the brand of Valeo.. it's half the price of a dealer one and the build is much more reliable.
Part number is 850358, take this to a local car parts dealer and they'll get hold of one for you. My unit cost £97.22 and I fit it myself, it's been working fine for months now. Hope this helps mate or if you've already managed to sort it anyone else out there with the same problem