Singapore Airlines (SIA) primarily handles bookings and support via their Contact Us page on Singapore Airlines or call centre in Vietnam (+1-866-829-1086 for reservations, 24/7 English support), as physical offices in Hanoi might be limited, but you can find addresses for their representative offices/agents, like those listed on Vietnam Yellow Pages (e.g., 222B Giap Bat St or 94 Luong Yen St), or contact the Singapore Embassy in Hanoi for official matters. Jauntlet.comhttps://jauntlet.com/