ICE: Complaint not upheld

Another update: I have received another 2 page of A4 size letter from ICE. I was hoping there would be a glimmer of acceptance of my ongoing compalints but no. The tone of the letter is a complete put down as if I am a nobody just making a nuisance of myself. I will quote from part of it. 
           "I have noted your comments around the standard of English in the HCP's report, specifically that it was not clear and concise and that the information recorded was inaccurate; Whilst the HCP may not have drafted their report as you would have liked them to, that does not mean the report was incorrect or unfit for purpose". They go on to say if they identify recurring service failures on the part of IAS they will provide feedback to DWP.
          Bearing in mind lies even with evidential proof are not part of their investigation they will not be reported to DWP by ICE. 
          The last paragraph states they are closing my case and if I contact them again they will not reply. 
 Permission to scream. This is the final "head banging against a brick wall" apart from the Parliamentary Ombudsman. Anyone got any experience of reporting a complaint to them. 

Thank-you @thespiceman I appreciate your support and friendship. I will investigate the websites you mention but there comes a time when you have to admit defeat. I do have a letter to send to the guy at IAS who wrote to me as he seemed a lot more caring of the quality of assessor's work. There's nothing to stop anyone writing letters but the answers may cause yet more stress. When I rejoined you recently I hoped that things had improved but reading recent posts they still look just as bad. 

Hi @Misscleo, I only have experience of benefit compaints but I would start by contacting PALS if I were you. That stands for Patient Advisory and Liaison Service. They deal with any problems patients have with Doctors/hospitals.