CHEYENNE, Wyo. (AP) — A Cheyenne utility says it has mailed refunds to customers who were overbilled since January 2005.

Officials at Cheyenne Light, Fuel and Power told the Wyoming Public Service Commission Thursday that they have fixed mistakes in customer accounts that resulted in more than $1 million in overbilling.

The Associated Press reports that the utility incorrectly charged franchise fees to some customers in rural Laramie County. The fees are normally charged to customers who live in Cheyenne, Burns, and Pine Bluffs.

About 4,400 customers were overbilled.

Residential electric customers received an average refund of $20 for each year they were overcharged, and residential natural gas customers received average refunds of $15.