There are several "sellers" who stalk the "dark web" here on the forum. Guys that NEVER post or hardly post, just stalk the WTB's and pounce on the sales. I ran into this when I first joined and wasn't thrilled with the parts I got. They just needed more elbow grease that I thought they should have. You just gotta look at guys who visit the thread and check their post count if they send you an offering of parts. If they have low post count or none, and also especially if they've been a member for years and are active daily.......bye bye, move to someone else. Sorry, I tend to over analyze things.
But, op, go back to PayPal and have them correct it if they can.