Aside from any civil action, I would suggest that law enforcement be involved if they haven't already. Get the contact of two fraud investigators in both Canada and the US, hand over all the info, and also put them in contact with each other. Receiving money for a service and not delivering is a crime, and it should be investigated. So, basically, "Remove the comments saying I owe you money for services that I never delivered and I'll refund the money I owe you for services I never delivered." He's nothing more than scum.