New corner shower is finally fitted!

Wall are covered with these panels
http://ceiling2floor.co.uk/product/p...t-grey-marble/
and very nice they are too!

10mm thick plastic, looks very similar to corrugated cardboard from the
side.

Problem is that there is no way to fix a shelf to the glass enclosure,
so it will have to be attached to the walls somehow.

Considering that it will need to hold around 5-6 full 0.5l bottles of
shampoo/conditioner/shower gel/etc, possibly more (don't ask...), would
any of the suction-type fixing be up for the job?

Otherwise, how would the panel suggest fixing it to the wall panels
(plasterboard behind)? Simple masonry rollplugs?