Help! How can I cover the cake in one piece of fondant without it ripping because of the bottle neck? I have covered on befor but did the neck and bottle separately and didnt like the separation.The cake is about 12 inches tall. Thanks!

Have you tried the wrapping method? It works well for tall and thin cakes. You end up with a seam at the back, but you can minimize it. Suggestions are to use very sturdy cake (pound cake) and ganache instead of BC under fondant.
Here's an earlier discussion string:http://cakecentral.com/cake-decorating-ftopict-656811.html