Hi Daniel,
Its gonna be hard to sort your spam problem unless you have access to the adminCP, firstly you'll need to install a few decent anti spam mods as a matter of urgency as well as moderating new members posts all done via the admin CP.
First you need to ask yourself, does this company really have an interest in the running of the forum and if they can't be bothered then perhaps they need to give someone admin control.
Its nice to see a moderator that feels for the site but in plain facts, unless you get admincp control, your not going to have a lot of luck.
I take it you have Moderator status? You'll be able to ban them at least, if i was you mate, i'd get in touch with the company and offer your service as admin, see what they say, if you get no reply then you'll need to think is this site really worth fighting for??
We all hate spammers here, and we do what we can to help our fellow members, but whats worst is a site owner who do give a dam about security issues like this.
Good luck and let us know how you got on