Unfortunately, the law puts the onus on you to ensure that everything is fully covered; you can't necessarily rely on the (admittedly logical) assumption that all charges would be covered if it was approved, especially given that you were aware it was computer-assisted--so you had the knowlege or information necessary to call the insurer and check to make sure it was fully covered. Insureds are responsible for all charges not covered by insurance, so as a general matter, you are liable for this uncovered charge.You could try fighting it, but given they insurance law works in our county--that assumption that you have to pay all uncovered charges, even if not aware of them ahead of time, plus the fact that you had written acknowledgement that there was computer assistance--the odds are against you; you'd have to show essentially that the charge was fraudulent to have a good charge of prevailing. Couple that with the fact that one or more of the agreements you signed (i.e. with the doctor or provider) very likely provides that if they have to sue you, they can collect legal fees, and fighting is likely a bad idea: low probability of winning, coupled with a high probability of increasing what you owe.