If you are having a problem with your dealer, I can think of a couple of things you can do to help yourself. The first thing you need to do is change your attitude and become a problem. You tried to be nice and that didn't work. The longer this situation drags on works in favor of your dealer.
Then you need to call your dealer and threaten him with 3 actions you intend to make good on. 1. You will call B&W, as well as follow up your call with a certified letter stating that your dealer didn't follow proper B&W protocol required for the sale and delivery of B&W speakers. Also tell him you are sending B&W all supporting and related documents. But that's it. Give no more information. The dealer will be trying very hard to bait you into giving him more info, along with trying to convince you that this course of action will hurt, not help you. Be disciplined, and ignore it all.
2. Now tell the dealer (and follow up in your certified letter), that you will be taking him to small claims court for whatever the maximum allowed in your state is (most states are $5000), plus all related expenses. You will be suing for just the damaged speaker housing, and no more. Don't worry if the part doesn't cost 5k. Always ask for the max and let the judge decide what you should get.
From past experience, I know that the instant I bring up small claims court, you'll get a bunch of posters telling you to not bother, for any number of reasons. They'll be wrong. The US small claims court has a set of rules and regulations that very few people know about. Its not the same as using a regular court.
3. Now its time to start talking about stopping payment on your credit card. Its important to complete the first steps I list, as well as anything else you feel is important. You're not just going too call your credit card company up and have them reverse payment on a pair of 25k speakers you already have in your possession. There will be an investigation an an adjuster will be sent out to look at the speakers. Showing the adjuster that you are already taking reasonable steps to resolve the issue will go a long way in getting the credit company to side with you.
You will have 2 obstacles to overcome when dealing with the credit card company. The first, is that very few people are familiar with speakers that cost 25k. Expect them to be naturally suspicious, and do whatever they ask in helping them assess the value of the speakers. Second, due to the amount of money involved, expect a fight if things come down to a refund. The chance that your dealer left the money he got from the sale in the bank account linked to card purchases is most likely 0. That means, if the dealer does not cooperate in refunding the money, the bank will have to use their own funds. They won't want to do this, so expect some resistance.
I hope this info helps you out. If you can convince your dealer that you will be taking action on 1 and 2, they should fix the problem right away. That's why sending them a certified follow up letter is so important. They know you're serious.