Talk to a lawyer. You might be able to get a court order forcing your provider to make your records available to you. You can also ask for money damages. If you win, you can also get lawyer's fees and expenses.
If you have a good case, a lawyer may represent you without a fee, and try to get attorney's fees from the other side. A lawyer might talk to you for free to see if you have a good case.
To find a lawyer, contact your local bar association.