I would advise you to seek help from your local Welfare Rights organisation; advicelocal.uk
You have not given any details as to why you beieve your claim should be backdated.
When you apply for WCA you have to supply a fit note unless you move from ESA support, time time limit starts from when your workcoach receives your fit note, you then go into the assessment phase (13 weeks) if you are successful then your claim will start from the 14th week.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems
