Hello - hope someone can help me here.

I have a Bifold door into my bathroom, no problems with the door but
the tracking guide thingy at the top has broken so it just swings
loose from time to time.

I did a tour of my local DIY shops (B&Q, Homebase, Wickes) and none
sell the tracking guide thingy on its own - the best I could find
today would be a new door and guide thingy all in one which is more
than I need.

Anyone know of anywhere I can get one either local (UK Midlands) or
Online retailer? I have tried searching, but without knowing what it
is called properly I am not getting anywhere...

Thanks!

Andy