Some people are only on their computers 2-3 times a week so they may not be refusing to contact you.
4 days after sale date you can open a non payer case. That can spur a payment or response from the buyer.
If not then 4 days after opening the case, close the case.
You get your fee credited back, buyer gets a strike and you are free to relist.
To open a case go to resolve a problem in the small drop down menu to the right of the item in your sold list.
But I usually wait at least 5 days after sale date before opening a case.
