EK is obligated to book you on a flight from MLE to YVR if it's their ticket and a flight was cancelled. That can be on their own metal or through one of their partners, like WestJet or United. You are not obligated to pay for a new ticket or accept a refund for a previously-confirmed ticket. This should not be your job to do - it's the reason why you have a travel agent. Your travel agent should know these rules and needs to contact Emirates to rebook you through YVR.