Hi Anne, I am afraid that you are not able to appeal against the withdrawal of your ESA as this is part of the recently enacted 'Welfare reform Bill'. If your condition has worstened to the degree that you believe you now meet 'support group' criteria you can ask for a 'supersession' (re-assessment) as time in the support group is not time-limited. To do this, you can just phone or write and ask for the appropriate form - but be warned that the onus would be on you to provide evidence backing up your claim.
Nothing on this board constitutes legal advice - always consult a professional about specific problems