(b) Once debt becomes delinquent, it continues to be delinquent and may be subject to collection by a comprehensive collection program . . . .
(c) For the purposes of this section, a “comprehensive collection program” is a separate and distinct revenue collection activity that meets each of the following criteria: ... (4) The program engages in at least five of the following activities: ... (D) Contracts with one or more private debt collectors to collect delinquent debt.