It is a bit unclear from your question how the hospital cheated you with insurance. But, otherwise, you can send a legal notice from an advocate and claim damages but for that to be valid, I would need to know more information.
Feel free to contact me at email@example.com or 7601090381
You can send legal notice through your advocate and can claim Bill
If you want legal advise then you can call me on mobile no 9359867870