Absolutely definitely close once the full 4 days are up; why would you give them any more time?  If they did not pay in 4 weeks, and do not bother to pay within 4 days after case was open, they are not very likely to pay.  Once you close the case, get your FVF fee back, you can re-list.  BUT make sure you add this person to your BBL, or they may bid again or bid on something else you are selling.