Thank you. Then, under the collective facts you've described, you are responsible for those costs.
In a different way, it's like if you were to go to a restaurant and ordered a $5 burger and the waitress asked you what kind of fries you wanted only to later get your bill and see that fries did not automatically come with the burger. Are you still responsible for paying for the $2 fries, too? Yes, you are.
In the situation you've described, you signed a document saying that you would pay for what was not covered by insurance. Thus, you are on the hook. If you don't pay, they can sue for breach of contract
I know that this is not what you wanted to hear but you deserve a candid answer. I wish very much that I could offer you an answer that was more favorable to your circumstances, but the law seems to be pretty clear. Had I been able to provide an Answer which might have given you a successful outcome, it would have been my pleasure to do so.
I hope you understand.
My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back. I am happy to address follow-up questions. Thank you for your business!