First off, Amazon refunding isn't for the faint of heart. So if you're going to have nightmares or feel guilty about essentially ripping off amazon then by all means get someone to refund you.
I don't know about paypal refunding service. But I do know about Amazon refunds. Amazon refunding works by buying a product sold by amazon or a product fulfilled by amazon and getting one of the refunders out there to refund what you paid.
Mind you, you actually have the buy the product at full price first before getting someone to refund what you paid. If you're planning to buy something expensive like over $500, then ask the Amazon refunder if they can refund the item you are buying before you order. Refunding doesn't take very long and after you have been refunded, you pay the Amazon Refunder either a percentage of the item's price or a flat fee.
As far as Amazon outside of US, you can use any amazon like amazon UK. But there are language barriers which is why most people use Amazon.com/Amazon.ca/Amazon.co.uk
As far as the process goes, Most refunders only require you to give them information like the order number. Most will
NEVER ask for your login info.
And as a final note, If you're going to buy this service; make sure you only do it once or twice in your LIFETIME. Because Amazon might take legal actions or ban you info permanently and you wont be able to buy from amazon AGAIN. Unless of course you change your address or use a VPN
If you have any other questions don't hesitate to ask.