I'm SO sorry you lost your puppy
You bought that puppy from Jeff Dane who is known for selling small dogs AND with health problems. You can do a search here or on the net - just type in Jeff Dane - and you'll see you aren't alone.
I'm sorry you went thru this but he is NOT a reputable breeder. While very small young puppies can have seizures - he should have warned you about this and you should have gone to the vet asap - Whatever he said to you was total BS. He should have told you to get to the vet right away. Which again - shows how much he doesn't care one bit about his puppies
Your puppy sounds like he was too small to be shipped and after hearing where you purchased him from - I don't doubt that JERK even thought about his size and the trauma of shipping either.
I would for sure be upset about all this - but you probably won't get anything back from him. Once he gets your money ...he's done with you. I'm just sorry for that poor puppy.
ps....IF You do get another puppy - Have Nutrical on hand and give them a little bit 2-3 times a day....( and please try to find a good breeder - that man is bad news.