Start at the beginning.
You bought something.
You received it.
You don't want it-- at this point the reason is irrelevant.
You asked the seller for a refund.
Did he ask you to return it?
Did you return it? Did you use a tracked service like ExpressPost?
Did he refund you?
OR
Did the seller ignore you?
Did you start an Item Not As Described dispute within 45 days of purchase?
Did you return the disputed item to the seller when you were instructed to, using a tracked service like ExpressPost?
Has the seller received the item?
Have you been refunded by either the seller or Paypal?
That's the system. It's been in place for a couple of decades now. Don't try to reinvent it. All that will happen is that you will go past the 45 day deadline.
