Identifying replacement part and understanding what is involved in any repair

2009 3 series cabriolet
When cleaning my vehicle today and retracting the hardtop roof fully into the
boot, I noticed some damage that appears to have been caused to the
surface of the simulated leather covering just to the outside of the rear
nearside headrest. This was a 3 cm tear in the material. On examining the
operation of the roof when in the process of closing it, I could see that a thin
"cord" on the same side, had frayed and become detached from an anchor
point which has a plastic sleeve. There is a similar cord on the offside which
remains intact.
It was possible to close the roof properly.
I have no idea what this part is called and whether this can be repaired
without recourse to a garage.
Any assistance appreciated.