Nobody can guarantee a number #1 position or specific ranking for your site for a given keyword phrase. There are simply too many factors beyond anyone’s control – the search engines changing their ranking algorithms, efforts made by competitors, and new sites being added to the Web.
Obtaining a specific ranking is analogous to managing a portfolio. Your financial advisor will do their best to monitor the stock market and other indicators and to make sure your portfolio is managed to the best of their abilities. However, your advisor cannot guarantee that your portfolio will be at a specific dollar value or even that the amount will be up at all by a given date.