You can edit your purchase (including quantity, billing information, or canceling your order) until midnight the day of the deal, or while the deal is still live.
To change your purchase, please sign into your account at www.groupon.com. Once you are signed in, you will see your name at the top right corner of the deal page. Place your cursor over your name and your account menu will drop down for you to access "My Groupons".
From "My Groupons", click on "Edit order" next to the Groupon you purchased. On this page you'll be able to make changes to your order: you can change the quantity, update the billing info, or cancel the order completely.
If it's too late to do that, you can reach us at firstname.lastname@example.org or call us at (888) 375-5777. Our Customer Support team will work with you to help make it right.
Oct 17, 2012