Jack Sprat wrote:

I decided to put it up again using
some special plasterboard fittings ( a circle of metal you screwed into the
plasterboard which had a thread in the middle to take the supplied screw.)
Needless to say it lasted a week and now I am left with big holes.

Err what the hell are you doing, using the towel rail for pull-ups? I've
hung dozens of radiators using those screw-in plasterboard fixings and
they are absolutely fine. If you're abusing the fittings to that extend
you'd be better off cutting a hole in the plasterboard then fitting a
wooden load-bearing plate behind the plasterboard then making good
before re-fitting the towel rail.