I was so afraid of this when I responded to your other posts about your little one this morning.
Yorkies are 36 x's more prone to Liver Shunts than any other breed but at this time Dr. Tobias still does not know what causes it. Maybe you should read these medical journals so you can understand what is happening with your little one.
http://www.livershunt.com/
The sad thing is your little one probably just does not have the strength at such a young age to survive what is happening to his small body. The Yorkies they can usually save are much older then 9/10 weeks. You will have to make a very difficult decision on what is the kindest thing you can do for your little one.
We just had a member of our Biewer club just go through this exact same thing on an 9 week old puppy and she finally had to let her go after fighting for her life for 2 weeks. She just kept losing more ground. It was all very sad.
Now here is the hard piece of advice I must give you if you are going to sue Petland. You will need to pull out your contract and see if a necropsy (autopsy) is required. Unfortunately, you will not be able to stop/sue the breeders as modern medicine still does not know why this is happening. Even excellent breeders can have this pop up for no reason except somewhere in the lineage (even as far back as 7 generations) some inbreeding happened.
My heart breaks for you and I wish I was there to put my arms around you as you make this difficult decision.