Oh my God.
YES...you were taken by a greedy lunatic....to tell someone go to walmart and fill him up with a dewormer is SICK.
I would report them to ANYONE you can ...PLASTER THEIR NAME ALL OVER THE INTERNET and file a report with the BBB...AKC and anyone else who will listen.
I don't have a problem with his size...thats the chance everyone takes when they have a preset notion....Any breeder,
if unethical, can show you ANY picture of parents - doesn't mean it's for real
The first red flag for you should have been multiple breeds - often they are brokers....and some kennels filled with Multiple Breeds are just feeding grounds for all sorts of parasites.....you take a big chance buying from someone like this.
BUT...I sure have a problem with them shipping a FIVE WEEK old puppy and telling you to deworm him - that is just SICK.....
Poor baby - I hope he will find love with you ....but that breeder scammed you royally.