BMW Repair: torn liner on convertible, convertible top, rear window

Question
We have a 1999 323i which we just purchased.  The liner immediately behind the rear window had pulled loose and strings or cords (which are used to pull the headliner tight around the framework) had popped loose. The dealership spent all day fixing the problem before we purchased the car.  We drove it home then waited a few days to retract the convertible top. When we did, the liner pulled again and now has the identical problem.
Is this common?  Is it easy and inexpensive to fix?  Thank you.

Answer
Jim, take the car back to the dealer and make them fix it correctly. It shouldn't be that hard if just the strings are broken. If there is more involved then it can get complicated. Check the operation in the service drive to make sure the top works.
-Evan