If you have already signed up with an energy re-biller, you can still say “no” when they make their follow-up call to you. Once you say no, the contract you signed will become invalid and you will not have to pay a cancellation fee. Your current electricity service will continue without interruption.
The ECPA also requires the contract to contain specific information, such as the method of calculating the contract price, or else you may cancel the contract at any time. You may also cancel the contract up to 30 days after you receive your first bill, if the re-biller fails to provide you with a copy of a voice recording of a telephone discussion within 10 days after you request it, or if you permanently move from the premises, or any time without cause, although you may have to pay a cancellation fee in some cases.
If none of these options works for you, you may complain to the Ontario Energy Board or file a claim against an energy re-biller in Small Claims Court.