CHICAGO (CBS) — The Citizens Utility Board on Monday released its first-ever report card on the state of Illinois’ electricity competition.

CUB says people who have switched to alternative electricity suppliers have saved anywhere from $92 million to $218 million in total.

“ComEd has been locked into higher-than-market priced contracts in recent years. That has given a lot of these alternative suppliers elbow room to undercut ComEd,” CUB spokesman Jim Chilsen said.

When those higher-than-market priced contracts expire in June, Chilsen says ComEd charges should drop significantly.

Chilsen says that the alternative electricity companies get an “A” from CUB for short-term savings to consumers.

However, they get an “incomplete” for other things such as reports of misleading or inaccurate marketing, lack of innovation, and whether or not they can keep up those savings when ComEd prices come down.

The Citizens Utility Board urges you to look out for misleading sales pitches from some of the alternative electricity companies. Don’t show your ComEd bill unless you’ve decided to switch and don’t think someone who says he or she is from the “electric company” is from ComEd.

CBS 2’s Dorothy Tucker reports consumers should be cautious.

When retired professor Glenn Manacher wanted to save money on electricity, he turned to an alternative electric supplier called North American Power and Gas. It offered 5 cents a kilowatt per hour, much less than ComEd. But he says the good deal didn’t last and doubled to 10 cents the next month.

“I was absolutely outraged,” he says.

CUB Executive Director David Kolata agrees customers should be careful if they are weighing alternative power suppliers.

“We’re concerned about people being locked into deals that may not be great,” he said.

Do your homework, but you might want to wait until June before you make a move, Tucker reports.

CBS 2 tried to contact several alternative suppliers, including North American Power and Gas. Some were closed for the holiday.

Intregys says it will remain competitive with ComEd.