How do i contact costi? For general information about COSTI and its programs, please direct your inquiry via email to [email protected] , or contact our Home Office. COSTI's Head Office is located at 1710 Dufferin Street, north of St. Clair Avenue West, in Toronto. Please refer to the Locations section for specific service location details.Where is the head office of costi located? Head Office. COSTI's Head Office is located at 1710 Dufferin Street, north of St. Clair Avenue West, in Toronto. Main Phone Number: 416.658.1600 Main Fax Number: 416.658.8537 Please refer to the Locations section for specific service location details.What does costi do? As the first point of contact that many immigrants and refugees have with Canadian society, COSTI’s Settlement Services play a critical role in helping them overcome the difficulties and barriers they face in re-establishing their lives.How many clients does costi have? Operating from 17 locations in Toronto, York Region and Peel, COSTI provides services to over 39,000 clients in more than 60 languages. We welcome your comments and suggestions about our website. Send us an email at [email protected] to tell us how we're doing.