It looks like there is an error somewhere. There are 3 credit ref. agencies so it could be worthwhile getting her records from Equifax & Call Credit. If they are the same as the Experian one she needs to go back to the bank with the evidence (including the papers about the Admin Order) and ask them to check again.
If they have referred to some internal bank record then that seems to be faulty & needs to be put right. She could ask them to check the Insolvency Service bankruptcy record (on their website) which should show she is not bankrupt. If she cannot get anywhere with them, she should put in a Data Protection Act request to get full details from the bank of all records they hold about her.