Bubble Wrap Insulation Supports for Greenhouse

Whilst insulating my Rhino greenhouse recently, I found that the plastic fixings weren't fitting well due to the heavier construction of the Rhino. In particular, the corner and end frame supports were slipping off due to the weight of the polythene. Whilst rummaging in an old box of fittings, I came across an end support which was purchased in the 80's or 90's by a company called Heron plastics Ltd. A Google search shows this company no longer exists. As you can see on the attached image, the gap and angle of the area that slides over the frame is smaller therefore gripping better. I have also tried a number of the usual 'cheaper' options. I contacted Rhino but they have only suggested using cropped head bolts within the frame channels which does address the issue of the corners or roof ends. Does anyone know of a company that produces a clip(s) more suited?

 

Maybe:
Greenhouse Shading and Insulation Clips

 

I use the same as @JWK but they weren't so good for the end frames, so I bought some bulldog clips which work well.

 

Not the cheapest but Two Wests did a wide range of greenhouse fixtures and fittings. I have a vague recollection that they may have merged with another company. Worth checking out.

 

I was going to suggest them as well @Allotment Boy

Two Wests and Elliott