Nah, get the lawyers in. Making assumptions based on the price of a 7.7 sea legs I'd imagine you can, I hope. Don't let them fob you off.
Your point if owning an 8 month old rolled boat is exactly why you shouldn't accept it, it's value will have fallen massively. If you'd rolled it, fair enough, it's repairable and like a car, tough luck. But YOU didn't roll it! At worst (though not ideal based in your experience, you'd rather have money back) you want a new or almost new boat. At best, it was never fit for purpose, money back with compensation for lost fun/use etc. go for the middle ground, money back.