Window Warehouse Ltd installed bifold doors at our local tennis club in 2012. Over the years, they have dropped a bit as they get a lot of use, and they needed adjustment, but otherwise they look as good as new.
We booked an installer to come to adjust them today (15-Sep-20). He arrived bang on time and they now align perfectly again. Window Warehouse Ltd said it was minor adjustments only and that they wouldn't charge us for the visit.
We're very impressed.