Good for you. Sometimes you have to stick with common sense and gut instinct.
Good luck to you.
Edit; One more thing, good decision on the antibiotics. As the saying goes, "if it aint broke,
don't fix it"!
Lets spank this fat baby in the butt and put it to bed...
All private sales are final. Period. Going further, all private sales are, "where is, as is", unless there is a written agreement, or an implied agreement.
If you are concerned about a bad reputation, offer to give them their money...