AUGUSTA, Maine (AP) Central Maine Power has delivered copies of some customer’s utility bills to state regulators for review.

The Office of the Public Advocate made the request for the documents to the utility last month in connection with an investigation into excessively high electric bills.

The office plans to review three consecutive months of bills for each customer who filed complaints since May 1, 2018.

WLBZ-TV reports the data Central Maine Power handed over on Wednesday included information from 1,380 complaints received in that time period.

The issue began when the power company started using a new customer billing system in October 2017. Utility customers reported receiving bills 50% or more higher than usual.