Budgeting Loans

A cl has filled in two budgeting loan forms, one prior to XMAS, which they say they never received at the Wolverhampton Office. So we asked for another form filled it in returned it this time registered sign for post. It was signed for at Wolverhampton, but they and Liverpool where the claim is finally processed and monies released from, both categorically deny receipt of the letter, even after I have attached the Signed for signature. Apart from a complaint; which is in hand is there anything else I can do?