Utility regulators voiced their frustration Tuesday over the complex rates charged by Arizona Public Service Co. and the way the company has handled a rate hike that dates to 2017.

Tuesday was the first opportunity the five members of the Arizona Corporation Commission had to hear from both APS and the people who brought a challenge to the company’s rate hike.

Some APS customers are hoping the regulators rescind or reconsider the increase, which was supposed to average about $6 a month on residential customers.