Elgg is developed by volunteers and offered for free. So, there's no sales staff. And I think the preferred method of all developers of Elgg (if it's not specifically about hiring for some coding job but rather more general questions) is posting questions here on the community site within a discussion topic. This allows to the questions to be answered by whoever sees it first and is able to help - and the questions and answers can be seen by others, too, who might want to know the same.

Also, if you want paid support, like website development and hosting, you can post in Professional service group. There are many developers and companies specialized for Elgg service and they can offer full support for your project.