Live Support Contact iframe - Spam Defence

I've integrated the live support contact iframe into my site. I've been using it as a contact form for a long time so customers can get in touch via my site. I get a lot of genuine comms through it but recently it's been getting a lot of spam.  I don't know if these are bots or human but some kind of captcha or human test would be an idea to stop this.  

Here's the iframe I'm talking about http://theitfolk.com/homeuser/contact_pc_repair_fife

As mentioned in a previous post, I don't use it for live chat now because there's no automatic 'unavailable status' when browser is closed.

I have considered switching to a different contact form, but given I pay for both service desk and remote support, I like to keep everything under one roof.

Even better would be the ability to use an iframe that allows for service desk to be incorporated into a website and not just a standalone customer portal.