Here are a few pointers:
1. One would wonder why this guy(don't know his real name) would take the trivial role of just being "Tony". There has to be more to his character
2. He wears white gloves (the person who closed the door of the secluded house where Bani got trapped) was wearing white gloves too
3. He knew where Bani was going that day(she told him)
4. He has access to the Saahil's launch party white board to scribble (I know the secret of 29th June)
5. He has access to Jai's room (to keep the letter there)
These were my two cents...