Cashless hospitalization rejected - Max Hospital not in network list

I have a health insurance policy from Niva Bupa with sum insured of 25 lakhs. Last week, my daughter had to be admitted to Max Hospital in Pune for severe pneumonia. When we tried to get cashless treatment, the hospital said Max Hospital is not in the network list of Niva Bupa. But when I bought the policy, the agent told me that Max Hospital is covered. Now I had to pay 4 lakhs from my pocket and I am trying to get reimbursement. Has anyone faced this issue? What should I do? Can I file a complaint somewhere? The TPA is also not responding properly to my calls.