I am sorry you had such a poor experience buying your first snake. Do talk to the breeder. Try to be calm and reasonable at first. Sort of, "I believe there was some sort of mix up when I got this snake, it was supposed to be a pastel. Did I accidentally get the wrong one ?" Not, "Hey jerk! What the heck do you think you are doing selling me a normal instead of a pastel, did you think I was so stupid I'd never know the difference?"
At least if you fake being reasonable, the breeder might be more willing to resolve the problem. Since this obviously isn't the nicest or most honest person out there, this approach might be better overall.
Of course, if the breeder makes excuses or continues to lie about what the snake is, then it's time to drop all pretense and tell the creep what for and let us know who it is so we can spread the word of the dishonesty.
Gale