Charges after discharge

In December we received an invoice a Total outstanding on the account and then one in January that shows more. When we ask them what was going on they send us a 3rd invoice with both of this amounts on double so how can this amount increase when patient was already discharged ? And now it shows it was charged on the 17 November but on the other invoices it doesn't show. It looks like ***** to me because the invoice can't change from 1 month to the next and don't even reflect correct.