I checked the rules and there were some charges that were justified, but $300 for some medical charges were not.
I never refused to pay for those fees, but I was not able to come up with lump sum payment in short period of time as they demanded.
I will not opine or give you advice on CA law. However, I will offer an observation based on your most recent post.
If, and to the extent you have determined payment is appropriate, it sounds like your challenge is financing payment. You want them to finance the payment and they refuse. So why don't you try to borrow the money from friends or family?
You might not want to borrow from friends, etc., but what's your primary objective right now - fighting with officials or getting your dog back?