Dominion Virginia Power Unauthorized Charges to Checking Account Richmond, Virginia

I set up a payment with Dominion Power, I later canceled the payment with Checkfree (the service they use for payments). The payment was canceled through CheckFree (I have the proof from their site). Dominion still took out the payment amount after it was canceled. Then refused to credit it back said it was CheckFree who didn't cancel it. I contacted CheckFree and they said the payment was canceled, they advised me to contact my bank. I contacted my bank and they reversed the funds. Now Dominion has put a hold on my account for NSF so I can not pay by check, checking account direct debit or any of their free payment services. They are requiring me to pay a fee to pay my bill. They also charged me a NSF fee not including the NSF fees I incurred because of them taking out the excess money, in the first place. BBB has been contacted and DOM is still claiming they did nothing wrong!!! They are such a rip off! Isn't there a law against business being a monopoly? They can do this because they have not competition and therefore know that no one can do a thing about it!!! It is not fair!