My name is ***** ***** I'd be happy to answer your questions today. I'm sorry to hear that this happened.
You have the ability to take them to Small Claims
Court for the amount they promised to pay for the dog, plus the filing fee. You're not required to reimburse them for any money they spent on the dog, because you're not the one who violated the agreement - they are.
In order to actually repossess the dog, you'd need something in writing that gives you the ability to take the dog back if they don't pay. Otherwise, you run the risk that they will call the police on you for stealing, because the dog technically belongs to them, even though they haven't paid for it yet (the money belongs to you).
Here is more information on filing a suit in Small Claims Court, with links to the forms.
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