seller who scam

I am having very bad experiences with Ebay and sellers. One seller sent me the wrong item. the seller is asking t pay return which will cost me US$30 (I live outside the U.S) for an item that cost me US$32.79. I have had sellers sending me the wrong item and asking me to give a positive rating in order to be refunded. I belive most of the positive rating are deceiving because they want the customer to lie on the ratings so others think that their items and products are good. do you think this is fair