Did you get the confirmation from ebay that the order was indeed cancelled? Is the seller in managed payments? People experience various problems with MP causing various delays. Moreover, if you paid with CC and seller is in MP, it may take 3-5 days to be credited to your account + any delays caused by problems with MP. It's been now 6 days so you should have it by now, presuming that it was indeed officially cancelled.
I would wait a day or two for your refund to appear in the account you used to pay for the order. In the meantime, I would contact the seller and ask if they actually see that your payment was deducted from their account and when it was deducted.
