How to fight against mehta's children's hospital, chennai

Dear lawyers and experts, I need your advise regd how to file a consumer complaint against Mehta's children's hospital at chennai. Yesterday, my son was discharged from that hospital and total bill was Rs.25383. Despite the insurance clearly approving an amount of Rs.22080 and balance(Rs.3303) for me to pay(based on non-medical expenses and co-pay), hospital authorities insited on considering only Rs.19500 on insurance company side and charged Rs.5883 to me. I made insurance company talk to them, still hospital authorities say during their final claim with insurance company, they would not get complete amount, hence deducting certain expenses on my cost. I feel being cheated by this hospital as they have charged extra amount despite insurance company making it clear they would pay Rs.22080 to hospital.  

   I've in my posession the approval email from insurance side containing the Rs.22080 approval note and also from the hospital side, the split up bill that they charged me Rs.5883 and Rs.19500 for insurance. when i raised this concern to the hospital, they abused me with vulgar words during the argument. Is there a way to file a consumer complaint against this hospital and get back my Rs.2580 (Rs.22080 - Rs.19500). please guide on the procedure to do the same. Hospital is at Chennai and i'm also from chennai.

Thanks,
Senthil