To the person on the bike you are too aggressive yourself. Yes, what they did was wrong but you are making the situation worse with things like rude hand gestures; which the police might view as provocation on your part. Just get a horn and try not to point in someone's face as you "ask" them to put the phone down.
And in case you are wondering I am not saying I hate cyclists or siding with cycle-hating trolls. I try to view each situation on its own merit and afford all road users regardless of their carriage the same respect and courtesy. It isn't easy because this is often a crowded country with so shortage of people who don't play by the rules, and it all stresses you out. But you have to control yourself if you want the complaint to be taken seriously. Furthermore, you lose control you lose your concentration and that is obviously something you don't want.
worrying.