CAN A DOG SITTER REFUSE TO GIVE YOUR DOG BACK IF ONLY PARTIAL PAYMENT WAS MADE?

If you're having a dispute I would recommend calling Rover support ASAP. As a sitter, if I didn't receive payment I wouldn't keep the dog, but I would call Rover myself. Though, all clients pay at the time of booking, unless the stay gets extended after he or she was dropped off, so full payment is usually made without issue. Is there a reason you didn't pay the sitter in full? Were those reasons clearly stated? Unless your dog was neglected or abused I'm not sure why you wouldn't pay them? Regardless, it definitely sounds like you should contact Rover support.

Why haven't you paid the sitter in full for services rendered? Since all Rover bookings are paid in advance, I will have to assume you did not return home to pick up the dog by the required time that was covered by your initial payment. The sitter has likely sent you a bill for the extended stay. That needs to be settled.

If your dog had been placed in a kennel/boarding facility and you came back to pick up after the agreed-upon time, the kennel would require that you pay up before you take the dog home. This is no different.

I would assume this was not a Rover transaction, because clients make a full payment to Rover, and then Rover pays the sitter. In that case Rover will not be able to help you resolve this.

If this was a Rover transaction and the client and the sitter agreed that only a half payment will be made, then you should call Rover and discuss how/when the rest of the payment will be completed and dog will be picked up.

Can a sitter refuse to give a client their dog back? Well, sure she can, because all sitters are independent contractors and they are responsible for their own actions and their business. In a case like that if it can not be resolved, then it's time to involve lawyers. Good luck.