Application to back date housing and council tax benefit

Can any one help.  My clients were required to hand in full bank statements to support their claim for HB./CTB.  They could not get these immediately as the bank wanted £5 for each and they had no money.  When they did eventually get the money and order the statements which took a further 7 -10 days.  They sent them in but council have only awarded benefit for 2 weeks.  stating that good cause was not shown and therefore they would not back date the benefit.

Does any one know of case law etc that good cause is shown if the person is in financial hardship and therefore cannot obtain the information required to support a claim.

This is not a question of backdating and if no express decision was made to disallow the claim (thus requiring a new claim), the award must be made from the week following the date the claim was made. 

Even where the initial claim is disallowed, a subsequent claim can be treated as an application for revision of that decision (see for example CH/3009/2002,CIS/701/1993, R(SB)9/84, R(I)11/62)