Within 10 days of the notification or mailing of a LEC written summary and not thereafter, except for failure to receive notice or other good cause, an informal complaint shall be filed by the customer or customer designee with the Commission.
52 Pa. Code § 64.151
This section cited in 52 Pa. Code § 63.15 (relating to complaint procedures); and 52 Pa. Code § 64.153 (relating to Commission informal complaint procedures).