Thanks Argonaut, that's really useful.
It sounds like ours in in similar condition. It originally stated going when someone put their weight on the sunpad whilst we were cleaning out the bilges. We had the side panels off that usually support the hatch so the sunpad moved a lot further than it should have done and wrenched one of the screws out. Its just got worse since and its soaking wet.
Its drying out nicely and I think these fastenings will do the trick.
Agree about the A4 v A2...I'm struggling to find anyone who can supply A4 without a long lead time.