Fidelity Creditor Service Inc., a Glendale collection agency, has acquired another San Fernando Valley debt collection firm, its eighth such acquisition since 2005, the company announced. Terms of the deal between Fidelity Creditor and Balboa Collections Service, in Northridge, were not disclosed. Fidelity serves small- and medium-sized businesses in the health care, retail and entertainment industries. Chief Executive Clint Sallee said the acquisition is another step in Fidelity Creditor’s growth “It is increasingly rare to find a credible company with long-standing clients, especially clients in our target markets such as health care and small business,” he said.