I expect the page you optimzed for boiler hire is http://www.allseasonshire.eu/boilers/boilers.php
- there is no boiler hire in the URL
- The H1 should be "boiler hire".
- The page does not have enough content (minimum 300 words at least)
- Keyword combination "boiler hire" is not found (enough) in the content
- Keyword combination "boiler hire" is not found in the 1st part of the content
- You have no external links on this page
- Its not a top link in your navigation
- etc.
Sorry to say but the site just does not looks optimized to me.
I would advice to take some time and read this: https://yoast.com/articles/wordpress-seo/ and than create a great page!
Good luck!
Ronald