1. Yes, it is a good case to file before the Consumer Forum,
2. Collect evidence from the hospital about the refusal to pay by the TPA,
3. You already have the evidence that they have finally paid the same bill,
4. File a complaint case before the local District Consumer Dispute Redressal Forum alleging deficiency in service and unfair business practice claiming damage and cost,
5. Make sure to add the local office of the TPA to ensure that that your local Forum gets the jurisdiction to try your complaint case.