I think the most appropriate way to inform the site of this kind of information, is to visit the "add a new number" section of this site.

The reason why they probably weren't listed is because you're the first person visiting this site to have this info to hand.  Whilst the very big organisations, which almost everyone deals with are already listed, there are loads of smaller ones, which aren't.  This is mainly due to finding someone who knows the numbers, or indeed someone who wants those numbers!!

Anyway, I'm sure the site admin are grateful for this contribution and after reading this post, will act on this information.  Welcome to the site Kirsty!!