Database user with privelege to create additional users

Hi,

I recently became a postgres user by subscribing to a web host with postgres support. I began by creating a database in my account and found that a user with the same name seemed to be automatically created. However, when I connect to this database and user I do not have priveleges to create additional users. I have tried both ALTER USER (with CREATEUSER option) and recreating the database user with CREATE USER (with CREATEUSER option) . All requests result in the insufficient privelege error. Is there a way to alter my database user to have the additional privelege? If so, how do I do this?

Regards