On the assumption that you retained a copy of the ESA50, send a copy (Recorded Delivery), to the the DWP, for the attention of the Decision Maker, and take a copy to the medical, and insist that the ATOS "doctor" reads it before proceeding with the interview, they should include it in the file they return to the DWP.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems