If you are in dispute with a contractor over the quality of work or the details of a service contract, this type of dispute is usually civil in nature and not a criminal matter for the police.  

To pursue the case in small claims civil court, the procedures are explained on the Ministry of Attorney General website Attorney General
You may also contact the Ontario Ministry of Consumer Services, Consumer Protection Branch at 1-800-889-9768 or Ministry of Consumer Services to file a complaint with them.  There is also valuable information on this website regarding Cancelling a Contract and Consumer Rights.  

Protecting Yourself

Prior to agreeing to a contract, ensure that you check out the business, identification, references and agency referrals to ensure their excellent reputation.  You may also check the Better Business Bureau website at Business Bureau  or call them at 1-800-862-0825 for inquiries or complaints.  Once you are satisfied with the company/contractor, ensure that you get a fully itemized contract.