Unfortunately, for all intents and purposes, the deal died when they actually pulled your credit report and came to the conclusion you couldn't finance the new rig. There is no action you can take to increase your credit score 100 points. The dealer knows you aren't going to be able to put down 50% and pay any negative equity on your current loan. Talking to the finance manager, negotiating on the MSRP and all the other things they didn't do won't change the situation. The salesperson did what they are taught and expected to do, get a potential customer into the dealership. Unfortunately, a deal couldn't be made, but it not really the fault of the dealer.