Oh my Gawd! Very glad this turned out as well as it did. And a good thing you chose a "small river".
First of all, limited warrantees apply only to the origional cost of the purchase. They aren't obligated to pay for anything beyond the cost of the item. That is assuming that you have a paper that came with the craft stating they offer a warantee.
However....most business people ( myself included ) are not jerks or idiots. I'm sure they'd offer a full refund. My Gawd, how could they justify NOT doing so? I wouldn't go making up lies about injury and destruction, but do ask that they reimburse you for your rod and reel. Judging by the name of the place, pick one out and suggest that you'd be happy with that model. They buy at wholesale, so they aren't out the full replacement cost. If they refuse, pursue Small Claims Court. Businessmen have little time to be drug into SCC for a couple hundred bucks when they know that your claim is justified. They'll probably replace it as a good will gesture.
Don't bother to sue unless this company ( the manufacturer ) has big assets. Most of the cataraft companies are not very big and don't have a lot of money. Your attorney would get most of it, and you'll get enough to buy the rod and reel and perhaps a burger on the way home.

Also, unless this cataraft was implied to be used in rivers, they may have an out by saying that you exerted far more stress on the equipment than lake rowing would entail. Backrowing, being what it is, could really stress a frame, especially if your in a seat with a back on it.

Hubby and I used to sell catarafts. I was rowing one and an employee was rowing one down the Elwha through the Rock Pick. I asked him if he felt confident going into it. Only THEN did he tell me that this was the first time he'd ever floated a river on anything but a big flat bottomed raft. Introduction To Back-Rowing 101 resulted in him pulling an oar out of the oarlock and sliding right up the side of a boulder. The raft flipped over him and the oarlock caught on his lifevest just under his chin. ( I truely thought I was going to see someone drown before my very eyes! ). The moral of this story is: Catarafts aren't as forgiving as driftboats, in manuverability OR constuction. REALLY check these puppies out for soundness of welds, strenghth of belts, cracks in framing, etc. They cost less because they ARE less.
And hey......fix that oarlock with something more than duct tape, please. Your wife will be glad you did.
Diana