I have a new theory.
Kahi aisa to nai, Ishqi would call out Mayank in front of everyone and Sonu would be too scared to accept and would deny something happened and then Mayank would call for police for "sabotaging his image etc".
Zada hogaya na..sorry
But Ishqi has a cellphone with msgs and Sonu's pics. It can easily be verified whose private number is that. Sonu can't deny it. They also built up Sonu-Ishqi bond, it would be really weird if they take that away. Ahaa has seen how Ishqi stood by Sonu everytime so he wont distrust Ishqi in this cse.