Cashless hospitalization rejected - Max Hospital not in network list

I have a health insurance policy from HDFC Ergo with sum insured of 20 lakhs. Last week, my father had to be admitted to Max Hospital in Pune for kidney infection. When we tried to get cashless treatment, the hospital said Max Hospital is not in the network list of HDFC Ergo. 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.