PC overpayment : change of circumstances??

Clutching at straws a bit here and looking for the customary get out of jail card. Here goes anyway:

Client was in receipt of PC and in August ‘09 a new Private Pension of £30 per week started. He thought he should tell the pension service of this extra money (although he didnt know how or if his PC would be affected)
He posted his bank statement and award letter to them and received the paperwork back with a small date stamp, dated 9th sept 2009. He thought no more of it and filed it away.
He had a visit from the pension service in December 2010 where he gave them the details again. At the end of May 2011 he got a letter saying there had been an overpayment from August 2009 as he had failed to tell the Pension service of his change of circs.
He came in to appeal this based upon the documentation posted in 2009, and that he had indeed notified them of a change. I examined the paperwork sent and he failed to notice that the date stamp on the letter wasnt actually from the Pension service, it was from the Royal mail” opened mail dept”. It now appears the letter never actually got to the PS as it appeared undeliverable (reason unknown) and simply returned to my client. As the date stamp was very small he didnt notice that it wasnt from the PS.
His argument is that he sent off the evidence in good faith and it wasnt his fault that the post office failed to deliver. How is this applied in the “failure to notify of a change” regs when he can prove it was posted?.He is also annoyed that it took them 6 months from the December home visit to notice the overpayment and the amount would be a lot less had they acted sooner after the visit.
Any ideas folks? Thanks

I’m afraid that if it is an established fact that notification wasn’t received then there is no defence against the overpayment unless he can established that the notification requirement was in ambiguous terms.  That seems unlikely in this case.  However, once the notification was given at the home visit then it is not recoverable from that point.

I appreciate his annoyance but the recovery of overpayments relies on strict liability principles.  In other words, it does not require the demonstration of fault or negligence on behalf of claimants.  It is a simple test of actual failure to disclose a fact one reasonably knows one should disclose (including ineffective disclosures) and that that failure to disclose is a cause of the overpayment.

Thanks Nevip. At least i got some sort of result as i can challenge the o/p from Dec to May.