Lone parent and Child Benefit claim

My client came to the UK from Pakistan in November 2005 to get married. Her husband was working and no benefits were claimed. Their child was born 10/01/08. Client did not have indefinate leave to remain, so no access to benefits. Therefore, her husband claimed child benefit. Her husband was convicted and sent to prison 14/05/10. The sentence is 5 years. He gave client his bank card, so she was able to withdraw the CB.
Client claimed IS as a single parent 28/05/10. She says she notified the person taking her claim that her husband was in prison and he was the CB claimant. She obtained indefinate leave to remain in July 2010 and obtaied an NI number in 2010. Her IS was backdated to when she made her claim.
She was advised to claim CTC, which she did in July/August 2010. In 2011 her CTC was stopped and client was advised by CTC to swap claimant roles for CB. She did this and CTC was reinstated and backdated to the date it had stopped. As her husband is in prison this was deemed a temporary absence and CTC is in joint names.
IS overpayment notice £4004.50 for 28/05/10 to 26/07/11. Failed to meet the conditions of entitlement as she was not in receipt of CB.
In the appeal papers it is stated on 02/09/11 client completed an A2 review form and stated CB was inpayment to her husband who is currently in prison. The decision re the overpayment was made 25/01/12 - she failed to disclose the material fact that she was not in receipt of CB.
However, neither the original claim form or A2 review form canbe located. Client is adamant that she has always told IS that her husband was CB claimant and he is in prison.
Sorry to have rambled on, but does anyone think this appeal has a chance of winning!

Yes, it is a ‘he said, she said’ situation and the DWP have no evidence that your client failed to disclose. I think this case is arguable.

I agree, and as a fall-back position it would be worth arguing that client had a route to IS anyway under schedule 1B (3) (looking after a child whilst the person who usually looked after the child was temporarily absent from home).

Thank you! I appreciate your help and I will keep the case open.