Cover for growhouse

Mine is manufactured by Hall's they supplied me with a new cover last year, no problem. Have a look at the assembly instructions, the manufacturer and possibly spares part numbers may be on that, they are on mine.

This is a B&Q own brand job seem to remember there was nothing on the assembly instructions, still will look them out and have a check. The distance on the width at the center of the curve seemed to be greater than the width lower down so shortened the stertcher by a mm each end now the cover shouldn't be under such tension, so it shouldn't "break" so easy. Cover has already been replaced with no questions so I am taking it to B&Q tommorow to see if they will replace it they should do but I have no receipt and can't prove the eldest son "hashed" it or if it "broke" because of a manufacturing defect.