Ya they should fit on the dexters. If you give me the measurements I can get you a quote on the axles. Generally get them cheaper than you can from a trailer store. Another thing to look at is how much weight is actually on your axles. I stepped up and put bigger axles under mine just for reliability. I put 3 4500 lb axles under mine but only have 10k on them. That way the axles are never near capacity.

To answer your original question:"What would I do?".

I would have been all over the dealer that represented the trailer was new. THEY should have contacted the trailer manufacturer if they felt the problems were related to defects in workmanship and were warranty items.

The trailer is a spindle trailer and it doesn't have bearing buddies. It just has the zerk fitting and thats it. You grease it until its comes out around the nut.
I just hope between all parties involved that this gets resolved so I can pick my boat up. I don't want to have to get an attorney involved for a $5k trailer.