I have received the very same threatening calls from this company involving an old 'closed' US bank acct.
They actually yelled at my husband and told him if he did not have access to the money, to borrow it from a neighbor or to sell something !!
I called them back and told them I was reporting them to the FTC, the oversight committee, and consumer affairs.
If indeed we owe money, I requested a statement, which was not forthcoming.
I received another harrassing call today, and was threatened with litigation.