my response to what you indicated above as "His last response", would be something along the lines of ...
if you want to be a d**k about it then I believe I'll get in touch with your boss's boss's Boss (is that in the UK?) and see what he thinks we should do about it. And in case you can't tell, I'm definitely not f**king around. You don't like the nice guy approach? OK.
I would prefer for it to be friendly, but if you're not going to work with me here ... when your buddies over at corporate B&W receive a link to this thread where all of these guys can also see how I've been wronged by you.
I'm thinking I may end up with a little sweeter deal than the one I'm currently facing, but I'm also pretty sure it's gonna come at your own expense. The way you're handling this, at the very minimum is dragging their brand thru the mud. They would never hear of this kind of service. And you're in sales? Dude.
Something about this whole deal was a tad shady from the beginning. It's starting to make a little more sense now. I think it looks like you were trying to offload a product that was at the very least, mis-represented ... when a piece of equipment is DOA then it does not! work as you advertised. Not sure how B&W corporate office is gonna look at it, but I bet they're not gonna appreciate that the deal is literally going down out of the back door of one of their stores.
I do know that I want my money back and you're going to pay return shipping costs or I'm gonna decide whether I want to pick up the phone and start trying to figure out who I'm gonna call or if I'd rather put the whole thing in an email and include a link to this thread. You have 24 hours to respond.
I'm pretty sure you can say it a little more concisely, but yeah I'd be a little more clear with him about your intention, and let him make the call whether you're gonna do it the hard way or the easy way.