> Surely he should have checked the money before he left here??
Oooh nasty! Yes, I think he should have checked before leaving, much as it could be said to have been difficult to stand there and count out the money. Especially as they may still have been upset at having to return the puppy - they could /should still have counted it when they were back in their car, before leaving?
I don't know how you can deal with this because it's their word against your's. I suppose you can but say you are certain you gave them back the right amount of cash (did you have them sign a receipt?) and if they continue to harass you, involve the police?
I hope the puppy is ok and at least you got her back.
Add - If these people are putting stuff on places like Facebook - there are libel laws!! If that continues, I'd be finding a good lawyer.