Hello 'vkharlip',
How long ago did you buy it? You say you've paid already? If you have already paid you will have to ask the seller to cancel the transaction and refund you. Depending on where you bought it, there is a good chance the seller will tell you it is too late because the item has been sent.
If you are told the item is in the mail (which may or may not be true) there is not much you can do. When it arrives you can ask the seller to accept a return, but if you just pop it in the mail the seller will likely say it never arrived, - meaning you end up with nothing.
Otherwise to return with Delivery Confirmation is very expensive, and sellers know this. Thus it may be in the seller's best interest to assure you the item is in the mail, knowing that will be the last of it. After all, it's not the seller's fault you bought the item.
If it is not a particularly expensive piece you may have to take the loss on it. But sweetly ask for the cancellation and refund anyway, - it's free to ask.
