I have been on eBay since 1999 and have have very few problems. I have yet had one that has not been worked out but sometimes it just takes a while. Slow shipping has been my worst issue with sellers.
Always check when the item was mailed. The date is on the postage meter stamp. Compared this to when you paid for the item. Should be mailed within a day or two unless the seller states otherwise. Most of the time slow shipping in North America is due to the USPS or Canada Post.
