He is lovely
whatever his breeding.
But I would also feel aggrieved by being misled by his breeder. It isnt very responsible as a show cocker and working cocker need different stimulation and exercise needs, and many could end up in the wrong environment.
I think you need to ask yourself what would you be satisfied with by taking it further? Is it to get some sort of a refund? To bring notice to others that your breeder cannot be trusted?
That will then guide you to the course of action you may want to take. Personally, a healthy, happy, loving puppy is the main thing, but if you intended to show or breed from him, I am not sure on that position.
Pat