AUGUSTA, Maine (AP) Over 200 Maine power customers have joined a class-action lawsuit saying they were overbilled by the state’s largest utility.

The Augusta-based law firm Lipman & Katz said in a statement Tuesday that it plans to file the lawsuit against Central Maine Power Thursday in Cumberland County Superior Court. CMP Ratepayers United has also been invited to join the suit.

CMP’s problems include customers seeing double usage on their bills with no cost and enrollment issues with auto-pay. Records show the company knew about the issues.

The Maine Public Utilities Commission recently authorized a consulting group to investigate complaints about the company. PUC officials are also investigating the utility.

Gail Rice, a spokeswoman for CMP, said the company hadn’t seen the complaint and couldn’t comment on the matter.