CHICAGO (CBS) — It’s unusual for three utilities and the Citizens Utility Board to come together for a single news conference, but they did just that Friday to try to prevent customers from being scammed.

ComEd said, so far this year, as many as 45 customers have been scammed of a total of about $5,000, by people pretending to be ComEd workers in person or on the phone. ComEd senior vice president Fidel Marquez said there were 40 such complaints from customers during the first four months of last year.

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Nicor Gas vice president Jim Griffin said, like other utilities, “Nicor Gas will never demand payment using a prepaid debit or ATM card, nor checking account. We will never ask for account or credit card information in any email.”

Senior citizens and non-English speaking communities are said to be most vulnerable, according to Marquez.

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Savvy senior citizen Ernestine Kincaid, of the Austin neighborhood, said she saw through a scammer over the phone saying, “I say if you are from ComEd, you should already know my account number.”

The utilities said, if they do plan to send someone to your home for any reason, you’ll usually get a letter in the mail beforehand; and if you suspect someone who says he or she is a utility worker is not a legitimate employee, keep your door closed and call the utility to check.

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“Fighting scams and rip-offs requires a unified effort from the entire community,” Citizens Utility Board spokesman Jim Chilsen said.