Asbo
You can complain to the assessor's governing authority, the GMC is relevant for a doctor, for a nurse it is the Nurses and Midwifery Council, for physiotherapists, it's the Health and Care Professions Council, and for paramedics, it's the College of Paramedics.
Just do an internet search for the relevant body to find contact information.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems