1. Some people think it is okay to carry on eating even after they hear the Fajr Azan. This is common with people who wake up late and their isn’t enough time for sehri. Only Allah knows why they think it is okay to carry on eating even after they hear the Fajr Azan, and some who wake up late start eating when they hear the Fajr Azan!
2. Aftar is to be done after hearing the Maghrib Azan. In the West, Azan isn’t allowed, so some people add 2-3 minutes to the time of Maghrib and then break their fast. At the same time, we have ‘intelligent’ Arabs and other people who actually break their fast 2-3 minutes before Maghrib time and think that it doesn’t matter! I have personally seen such people.
A fast is ruined if a person indulges in any of the two deeds above. A person should leave a gap of at least 2-3 minutes before Fajr time starts and should break his/her fast 2-3 minutes after Maghrib time, especially if they live in the West.