Most sellers allow a week but it is your choice but after 4 days you can open anon payer dispute and 4 days later you can close it to get your fees back, they get a strike and are blocked from leaving feedback.

After the 4 days has passed from opening the dispute YOU will have to close the case as it is does NOT happen automatically.

Do not leave any feedback at all.

By issuing a non payer strike the buyer will be blocked from buying from seller that have the blocks in place for non payers with strikes.

To put these blocks in place hover your mouse over account in your my eBay page and from the drop down click on Site Preferences then go down the list till you see Buyer requirements and to the right of that click on show then click on edit. From there you can put in place the blocks you want, to stop those you want to block from purchasing from you.