Although eBay have now set up Buy It Now listings to automatically relist until such time as the item sells or the seller pulls the listing, given that you've got all of your listings set up in Auction format that shouldn't happen. You can, however, manually choose to have your items automatically relisted when you set up the listing - if that is what you did then deactivate the Automatically Relist function and the adverts will not relist if the advert reaches the end of its listing time without having attracted any bids. However, if you've chosen to list using the bog standard selling form then this is probably why you're experiencing the problems that you mention. In order to stop this from happening end the listings that you do not want to automatically relist, then if you do wish to relist them (or anything else that you haven't yet listed) use the Advanced Selling Form, sometimes referred to as the Business Selling Form. Some users report seeing a lot of eBay blurb about Advanced Selling Form/Business Selling Form as only being suitable for business sellers - if you see anything to that effect then ignore it, as it's a load of hogwash and it is suitable for any seller to use, whether they are a private or business seller.
You also mention that there is no option to select the Advanced Selling Form. If you click on the option to sell an item you should see a new page load up, with two options in the top right hand corner of the page. One tab is for the bog standard selling form, which you should avoid at all costs, whereas the second is the tab for the Advanced Selling Form, which is the one that you ought to be using if you do not want eBay to keep on butting in and changing aspects of your listing without your consent. If you list using the Advanced Selling Form then it will be you who gets to have the last word as to which options you choose to include and exclude from your listings. If you do not want your listings to automatically relist if they do not sell then avoid listing using the Buy It Now option and set the listings up in Auction format. Set the starting price up at the minimum amount that you are prepared to accept for the item, making sure that you set it slightly higher than that amount so that you still get your minimum price once eBay and PayPal have taken their cut of the final selling price, and hopefully things should start going right for you.
Good luck with your future sales. If you get stuck and require any more help feel free to post a query on the forums, as there are always plenty of people willing to offer advice to people who need help.
