If it is truly a duplicate charge and clear in the contract (rather than, for example, a destination fee plus a dealer fee) you can tell them you want a refund of the duplicate fee or you will report them to the FL Attorney General’s Office (and follow through if they don’t refund the duplicate fee). You can do this without an attorney.
I think you are SOL on the financing if you accepted the terms.
https://www.flhsmv.gov/safety-center...er-complaints/
Edit: I see ScottSinger already suggested right before I did.