(a) Pending the hearing and a decision, the commission, after delivering to the utility a written statement of the commission's reasons, may suspend the rate change for not longer than 150 days after the date the rate change would otherwise be effective.
(b) The 150-day period prescribed by Subsection (a) shall be extended two days for each day the actual hearing on the merits of the case exceeds 15 days.
(c) If the commission does not make a final determination concerning a rate change before expiration of the suspension period, the commission is considered to have approved the change. This approval is subject to the authority of the commission thereafter to continue a hearing in progress.