When you do the exchange,please have someone with you and do it in a public place. I would even recommend having her meet you in front of the police station and do it there. 
Also have some kind of paper/statement etc., saying that you are refunding her money and getting the dog back. 
Perhaps if you could make the exchange in front of the police station you could also get an officer to come out and witness the exchange,that way if theres ever any "question" you would have someone in addition to whomever you bring with you to verify things. 
Hoping everything goes smoothly for you.     
				__________________    Member Of The CRAZY Club        |