not happy with reliance in Mississauga

We just sold our condo and the new owner is saying that she does not want to pay the rental fees of $25/mo and refuses to sign off on the paperwork to set up the Pre-authorized payments from her bank account. As a result, Reliance is still withdrawing $ from our account every month even though we no longer own that property. They say they are legally allowed to do that??? Anytime I call I just get their voice mail with no option of waiting for the next available rep and then I get told someone will contact me back within 48 hrs. It is impossible to contact a live agent in the billing dept when I wish to. I have called 5 times over the past 3 days and I have gotten "disconnected" 3 of those times. Their customer service reliability is garbage. Apparently they said our only option to get the $ back is to take the new owner to small claims court. I much prefer Direct Energy - they are a lot easier to get in contact with. Based on this - I will not refer any of my friends to Reliance.