Selfdrive deposit refund

Hi everyone, I booked a rental car from selfdrive app for 3 months and paid security deposit. Now it's been 2 months since I have returned the vehicle and they have not returned the deposit amout. I have called them multiple times and sent emails but there is no response. I'm not sure if they have office here. I don't know how to contact them. Can anyone guide me if I can register a complaint in consumer forum or any specified office. Thanks in advance.