I sold a puppy on gumtree and the person I sold it to came to view and paid a $250 deposit on the puppy and they were extremely happy. A week later my partner has a private message on Facebook from the buyer, saying that they want a refund because she is divorcing her husband. I had a message on messenger too, saying she wanted her deposit back due to concerns on the yard size. I sent them an article on the breed of dog and they said they would keep it. They then said they want a deposit back. We said if they want we can meet in person as this was all very unsettling. They took days to respond and eventually didn't. 2 months later we have had a message from the ex husband demanding it back and saying they want it or they will "take this further". Can they actually do anything? do we need to give the deposit as this has been such a big inconvenience and stress to us?