Well, it depends on how well I knew the seller. I would probably be relatively patient right now just because it is an extremely busy time of year between Christmas/New Years. If the seller is a respectable person, you should be able to stay in contact with him/her so that you have a reasonable time frame for a refund... But again, this is an extremely busy time of year so I'd try to be as patient as possible - within reason.
Now, if you sent the cue back like a month or two ago... I might be of a different opinion. However, I try to buy cues when ordering through the mail from people I'm very confident in... so that when the cue arrives, there should be no reason to send it back.
But for curiosities sake, how long has it been since the cue was delivered back to the seller?