Wow, so this is clearly in the past and they still want to charge you a redeposit fee? Unbelievable.
I've actually had some good luck with agents lately regarding redepositing miles from waitlisted awards. Both knew the policy that if the upgrade hasn't cleared (i.e. still on the waitlist), you can have your miles back at no charge (although the second one had to ask a supervisor first). Both times my mileage showed up within minutes of hanging up the phone.
I know you said you've made several attempts to contact UA, but keep trying as there are good agents out there somewhere!