Electric rear window mechanism

Over the weekend I had a slight mishap with the rear window in my Octavia. The glass dropped into the door pannel when I was putting it down via the switch up front.

After a visit from the RAC man it seems "something" that holds the window onto the runner has broken off. The motor itself still works as you can see it moving up and down. Constructive use of a cable tie means my window is now firmly shut. I just wondered if anyone had any idea on the cost of fixing this - as my car is an X reg I feel it may be more than the car is worth!

It was never the engine that was going to go wrong....