(a) If the public utility underbilled the customer, issue a bill to the customer for amounts the customer owes the public utility in accordance with subsection (2) of this section; or

(b) If the public utility overbilled the customer, refund the customer for amounts the public utility owes the customer in accordance with subsection (3) of this section.

(2)(a) Except as provided in paragraph (b) of this subsection, when issuing a bill under subsection (1)(a) of this section, a public utility:

(A) May only collect amounts incorrectly billed during the 12-month period ending on the date on which the public utility issued the last incorrect bill; and

(B) May not collect amounts incorrectly billed more than two years before the date on which the public utility identified the incorrect bill.

(b) If an incorrect billing described in subsection (1) of this section is the result of fraud, tampering, diversion, theft, misinformation or other dishonest or unlawful conduct for which the customer is responsible, the public utility may collect full payment for any amount that the customer of the public utility owes the public utility.

(3) When making a refund under subsection (1)(b) of this section, a public utility:

(a) May only refund amounts incorrectly received during the 12-month period ending on the date on which the public utility issued the last incorrect bill; and

(b) May not refund amounts incorrectly received more than three years before the date on which the public utility identified the incorrect bill. [2013 c.170 §2]