Regarding technical issue in brocker app

Hi @nithin Sir/ Team,

My cousin has other brokers account and had placed futures buy position in intraday(2 years back when margin was provided). Due to technical issue at around 3PM on their app (brokers app), position was not closed and open till next day.

Next day market was down by ~1000 points and position went into negatives. Now broker is calling each week and adding interest on it. As a customer/ user what steps we can take where it was all Brokers fault.

Thanks,
Nikhil