The ListHardBouncingContacts method is obsolete please use ListHardBouncesContacts2.
This method retrieved a list of all the contacts who hard bounced when sent a specified campaign.
||This is the username from your API key. It is in the format of an email address and will look similar to apiuser‑email@example.com
||This is the password from your API key.
||This is the Id of the campaign you wish to query against.
The result is an array of contact objects; the datafields will not be returned.