Sticking plastic to plastic

Depends on whether you mind the plastic surface being damaged - airfix type glue would be a good bet, but if you remove the hook the plastic surface will be damaged. Window fitters tend to use a type of superglue. Evostick impact type of glue would be ok but it is worth roughening the plastic surface first - surround it with masking tape then sand the surface to fom a better key.

Thanks for your help. Unfortunately the hook is mounted on a suction cup plastic and I feel that pressing the suction cup to make it be in total contact could still be a problem Blair

Try Silicone Rubber sealant. Baz

I used Evostick and had success. Thanks Blair

I had a similar problem with a small rear view mirror in the car that I use to keep an eye on the rugrats. After a while it would fall off, so I used some clear (because it would be seen through the glass) very thin double sided sticky tape covering the whole suction cup surface and it is still hanging on!

HTH

John