No WCA and, therefore, no WRAG or SG addition - Ex Gratia payment?

My client, who, due to the delays occasioned by whomever is responsible for the administration of the WCA appointments, was claiming ESA for about a year only getting the assessment phase - amount £72.40 a week at the time.  He has now started work so has missed out on the additional amount and will not, I assume, be called for a WCA now.  As he has missed out on potential extra monies by way of the WRAG or SG elements, due to a failure to call him for assessment, would this not be seen to be maladministration and , therefore, be subject to a request for an Ex Gratia payment to the amount equal to the potential loss of income.

Thoughts, as always, much appreciated.

Thank you in advance.

Patrick

Slightly different circumstances, whilst waiting for the ATOS assessment, my client hit the retirement age and started getting SRP.  She phoned the helpline and was informed that nothing could be done.  I wrote to the GP and had really supportive report pointing to her SG entitlement.  Then I wrote a letter with enclosed GP report to the Director General of Operations for the Department for Work and Pensions @ Caxton House, Tothill, Street, London.  SW1H 9NA
And she got paid the claimed SG addition of £35.75pw.  Happy ending!