Singapore Airlines (SIA) serves Jakarta (CGK) with flights, but their main physical office info points towards contacting their Singapore Airlines contact centre for support or booking, with contact numbers usually found on the Singapore Airlines Indonesia (id) contact page or by searching their Help Centre, as local office details vary or are for cargo/corporate, not direct passenger booking. You can book online or via agents, and for immediate help, use their customer support lines. Jauntlet.comhttps://jauntlet.com/