as @djbonner states .... this is already available ... and is also provided via a quick-link on your "My giffgaff" home page.
Useful giffgaff shortcode numbers
You would have done better to post a comment on the original guide, rather than copy and paste and removing the font colours originally used. This would have bumped it up the forum thus allowing it to be seen easily .... in a much better way than this one has.
Nice thought to help others though 🙂