The seller can set a percentage of the refund and can refund anytime. But please talk to the seller first and see if you can come to a good agreement. We do our best all the time to make you guys satisfied
Also please remember it costs time, money, resources, and energy for sellers to delivery clicks to buyers. Its not like a piece of software or ebook download where the seller just sends you a link and it doesn't cost them anything, when you buy a solo the seller has to deliver actual people to your link and its not always easy.