Yes, Clickbank can do this, but there are 2 restictions (in my book) 1 you give the buyer 8 weeks FREE use of your product and they can get a refund EASIER than Paypal (and it is abused)
You have to pay to get your ebook listed and they vet it, if you dont agree to their terms ie, 8 weeks money back guarantee, they will not accept your product AND it must be YOUR product.......
Ive sold there for 2 years, once you pay its OK, I get around 15 refunds per month, but I know they are unfounded. Yet again, another situation were people think they can get your product for free.
Dont get me wrong, if a buyer has a genuine reason for a refund I have no problem in working with them, and refunding them. I even give FREE yrchnical support!!