I think you might be able to sue for damages, not just the interest charged but also on the opportunity cost on the 7.1K fund for four months, but also the time spent dealing with them.

Or you can even attempt to discharge the contract of its entirety due to conditional breach as opposed to warranty breach(though you chance of succeeding is low).
Contracts need to be formed with good faith, which doesn't seem to have been displayed here on AC's side.