Sellers do not have to accept a cancellation request.

Have you paid for the item?  If you have,  and the seller has a Returns Policy on their listing,  on receipt of the item,  you can return it for a full refund,  but you'll need to pay for that tracked return postage.

If you haven't paid,  the seller can issue you with an unpaid item case giving you a  strike,  after 4 days. 

One strike will not affect your account,  but if you gain another,  you will not be able to buy from the majority of sellers for a full 12 months.

@lanadelrny 

It's best not buy items that aren't tangible from any online seller except for the brand's own website.

Can you link us to the listing please and then we can work out best way for you to proceed to get your money back.

Okay, I've found the listing and, if you look at the delivery details, there's an estimated delivery date showing.

One day after the latest delivery date you can open an eBay item not received claim.  Pop back here later if you need help with that.