Blocked card

Last month I lost my children's grant via post bank card I reported it. This month my card is blocked because they say they are investigating, they didn't inform me when they block the card and when I call I'm told to send certified copy of ID and I did but when I do follow up I'm told to send certified copy of ID and certified copy of bank card and the problem is there's no direct person to resolve this issue everyone is telling what he think is right, I just want my children's money that's all because there children are suffering while their money is stuck out there . Please help a vulnerable mother