My problem is similar, but more extreme: I need a complete greenhouse door and have experienced the same 'vacant' looks at BnQ.
I am having great difficulty finding any information on doors, alone
If you do receive any general advice on replacement 'doors' please forward me any info, if you don't mind.
(my geenhouse is 8x6 feet and about 7 feet approx high - looking at standard models in garden centres i guess any single sliding door would probably fit.)
Muh appreciated.
dean