Can I get my money back after being billed twice for the same procedure?

On March 29, I had a tonsillectomy due to reoccurring tonsillitis. On March 20, I received an estimate from the hospital saying that they would charge my insurance $27,000 and my responsible payment would be $5000. I have a high deductible plan and my coinsurance is only 50% but I was still surprised by this number so I gave them a call. During the call, I asked him what the out-of-pocket price would be. They told me the out-of-pocket price would be $2100 since they give cash a hospital discount. I decided not to bill my insurance and just pay out-of-pocket price since it was less than half of the insurance price.

The surgery came in and everything seemed fine. On April 5, I received an updated bill from the hospital saying I was responsible for additional $51,000 for the remaining surgery cost. I immediately called the hospital asking why I was charged this additional amount and how it could be so different from an estimate I received.

I haven’t received any resolution and have been waiting for their response. I’ve been told it’s been escalated and I should receive a response. Also during this time my insurance informed me that they were billed for the tonsillectomy and I had to pay the remaining. They were charged $600 and my responsible payment would be $500. I was again shocked that the estimate I received initially could be so wrong.

I feel misled and obviously would not have paid the out of pocket amount had I known the actual billed amount to insurance was so reasonable.

What are my rights? Ideally I’d like a refund of the $2100 and just pay my insurance $500. But I’d like to know if anyone has dealt with this and if they had issues getting money back.