The CAA has changed its environmental report form FCS1521 so that it can be used also to report refusals of access to airspace. The form is available here . We understand that the filed reports go into a database and the reporter is issued with a reference number for that event so it could be followed up.
Any pilot who is refused access to airspace or needs to report any other airspace related concern is encouraged to submit a completed form to the CAA. The same form is also useful to report when we, as responsible aviators, do contact ATC even where we are not strictly required to – and end up getting attempts to control us or keep us constrained in some way as if we were flying in controlled airspace.