(CBS) -- Unexplained spikes in electric bills have left some folks stuck with huge bills and lots of frustration.
CBS 2's Dave Savini investigates.
Jacqui Briggs says her electrical bills spiked about 400 percent. Her usual $50 monthly bills have grown to as high as $247, she says.
In her 30 years living in her roughly 900-square-foot apartment, she had never received any bills even close to this higher level. She also questions how Commonwealth Edison (ComEd) could say her electricity usage increased some months by as much as 756 percent.
"How can you prove you didn't use electricity?" Briggs says. "I don't know of any way to do it."
She had ComEd check her meter multiple times and even hired an electrician. All told her there were no problems.
The big bills lasted a year. Then, without explanation, the bills went back down to normal.
"Suddenly went away after a year," says Briggs.
She's not alone in getting unexplained spikes.
Renate Lux shares an apartment with her business partner and says the normal $40 to $80 electric bill spiked for months to around $800. That is an increase of as high as 2,000 percent.
Lux thinks it was caused by a defective meter.
ComEd workers checked the meter and a company spokesperson says it was fine. Lux says that cannot be because the small apartment was being billed for the same electrical usage as the neighborhood laundromat, which is constantly running machines and lights.
The utility did install a new meter, then the bills went back to the $40 to $80 range.
"If it wasn't a defective meter, why would it go down to normal when another meter was put in?" Lux asks.
ComEd still wants the big bills paid -- nearly $4,000.
"That's ridiculous," Lux says.
In the same building, another resident's bills spiked, too. The owner of a 900-square-foot apartment started getting bills of more than $800 a month. ComEd says that meter was tampered with, causing the spike. The owner, a retired physician, denied this, but was billed, anyway, through his automatic debit account.
The unexplained spiking bills has left him and others frustrated.
"They can shut you off and go, 'Well you owe this money -- pay it or too bad'," Lux says.
A Commonwealth Edison spokesman says the utility is committed to ensuring customers receive accurate bills. This week, CBS 2 received more complaints of unexplained spikes that also went back down without explanation. Most of the cases happened last fall.
The Citizens Utility Board is looking into these and any other cases. You can file a complaint online or by calling (800) 669-5556.
Commonwealth Edison Statement regarding Jacqui Briggs:
ComEd is committed to ensuring its customers receive an accurate bill. The customer contacted ComEd last year and upon receipt of the information, ComEd immediately went to the customer's home to inspect the meter equipment and found it to be working properly. When we share these kinds of findings with the customer, it is our practice to recommend that the customer contact an electrician to conduct a thorough inspection of the home's electrical system to help determine the cause of the additional energy use. We will continue to work with the customer should any additional information be presented.
Commonwealth Edison Statement regarding the two units in Renate Lux's building:
ComEd is committed to ensuring its customers receive an accurate bill and prioritizes responding quickly to any questions customers raise. Upon receiving the customer's inquiry, we immediately investigated by pulling his bill and traveling to his building to inspect his meter. We determined the meter was reading accurately but ComEd nonetheless replaced it at the customer's request. Regarding the second meter, as the customer indicated, ComEd detected signs of tampering at that location, sent a letter, and levied a fine.
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