Ginger
I knew they did this for Income Related ESA, as my wife, who is herself disabled, was "invited" to a WFI, but I didn't think they would for ESA(CB) as you are not included in the claim.
That aside, it's because you do not work, and the system is not clever enough to realise that this is because you have been unfit to do so.
I'm afraid, for ESA, attendance is mandatory, the best you might be able to do is have it deferred, but I think it unlikely that you will be able to do this for any significant period.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
