POssibly,you could escalate the matter to a USAA supervisor, who could then actually verify the payment has been received and applied against your account. Seems to me that USAA is a pretty well established financial agency (I'm also a new member), and that USAA could some how verify receipt of payment. Now, if you paid by personal check, or money order, that could possibly hold up the actual credit on your account.
And, also, it would seem that the oral surgeon would be willing to accept payment within 10 days of helping you. Possibly find a more understanding dentist/oral surgeon. This is a tough one.... but, don't give up!!!