I would think sending them the cork should be enough. Wineries realize they do occasionally have bottling problems. If they'll take them back at a restaurant, I can't imagine they wouldn't from consumers.
occams_razor-The same thing happened to me, except it was at a nice restaurant. The wine turned out to be very bad. It was almost like they were pushing to get rid of them. I did complain and did not have to pay for the wine. They also comped a desert.
Consider this: Call them and let them know that you are tied into a large group of wine afficionados. If they do not make good your purchase tell them you will go public with their poor response. Tell us where you bought it. Give us their e-mail address and phone number. I would be happy to call and express my disappointment in their services.
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