This is difficult usually it would be recommended to open unpaid item cases, this ensures your seller fee back after 5 days when you close the case, but gives the buyer an unpaid item strike. The two strikes they would receive here would stop them buying from the majority of sellers for 12 months. Understanding the reasoning behind their decision not to pay perhaps unpaid item strikes here is harsh.
So personally I would send cancellation requests citing buyer requestst to cancel, explain to your buyer they have to accept this for your seller fee to be refunded back to you. Go right of the item and from More Actions you can select Cancel Order and you must select buyer selects to cancel.
Should they ignore the request, you close it yourself after 10 days, fees are thus refunded.
