Andy
A Tribinal would copnsider a complaint to ATOS with regard to the ESA medical as relevant evidence, and some of the other Mods have confirmed that they are aware of Tribunal hearings being delayed while these are resolved.
That said,there has been a massive extension to the time that Tribunals are taking, so it may well be that now, the impact is minimal.
I am not sure where you might find statistics on this, ATOS certainly publish their complaint statistics, but I don;t think I have seen anything related to timescales.
Nor have I seen the Tribunal Service publish anything on adjournments or the reason, although they probably collect the statistics.
In theory a FOI request to both organisation should provide you with the information, but organisations are not obliged to produce information where there is a significant cost to them in doing so, which is often the case, for info that is not normally produced, or at least that is often the excuse.
Hope this helps.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
