Returning of deposit by You broadband

I had You broadband internet connection where I paid a deposit for a modem. I have deposited a modem before two and a half months and as per their rule, I should get a deposit amount within 45 working days. I had a correspondence with concerned authorities and I got a stereotyped reply. There are no phone numbers only e-mail ID for appellate officer and I sent three reminders but in vain. It is a very serious matter even after constant reminders they are not bothered. How long I have to wait for my deposit or will it be 'Chalta hai' more