Cancelling an order that I already refunded

[bamboobones-100]

Hi! I had a buyer purchase something and they wanted to buy a few more things. Long story short, this buyer was crazy and was using semi-abusive language. I let them know we will not proceed with this if they keep sending those kinds of emails. (I received probably 10-15 emails in like 8 hours from them) I ended up blocking them so they couldn't purchase more and i refunded through pp for the item they had paid for. How do i cancel the order through ebay without double refunding??? THanks!!

Jess