I returned a damaged item that was part of a mutliple purchase, but no money back. What should I do?

[aswellasyou]

I bought four items from one seller. One of the items was stained so she agreed to return my money plus return postage costs on receipt of the item. I sent it to her by recorded delivery and she signed for it two weeks ago. I've sent her emails asking for my money to be returned but have had no response or refund. I know I can do a dispute though either eBay or PayPal but how do I get either of my postage costs returned when they were combined postage? She charged me £6.50 and it cost her £2.48 for the stamp. I've then paid £1.50ish for return postage.
I'm not impressed and want all the money returned to me without a fuss but I don't think that's going to happen now. Should I dispute via eBay or PayPal?

[fergoose]

open a dispute for your original payment - unfortunately there is nothing you can do if the selling refuses to refund your return post

open it with paypal, and escalate straight away - seller has had long enough