Yes. You should start by contacting your host and asking them to open UDP port 27015 INCOMING AND OUTGOING. Since you are already on the phone with them, you SHOULD also ask to open TCP port 27015 INCOMING AND OUTGOING.
However, if your Game Server comes with free site hosting as it should, you are a lot better off using their hosting for your sourcebans site. For starters, their 27015 ports are already open. You also will be able to use 'LocalHost' instead of an IP address in the 'host' line of the sourcebans section of your database.cfg file.
I spent many hours trying to get Sourcebans to work correctly through a different host than my game server. As soon as I decided to use my game server's web hosting, it immediately worked.
First try:
www.insatiableforum.org/sourcebans
Winning try: insatiable.site.nfoservers.com/sourcebans