SMS Subscription Service charging HUNDREDS on the phone bill. HELP!

So my mum's freaking out. She must have signed up to something dodgy on the computer. She's getting these messages for something called Champions Quiz. I'm guessing its this http://www.champions-quiz.com.au/

She just got her phone bill, has $100 odd extra charge for 3rd party sms at $6.60 each. I became aware of it when she received 12 messages in 5 mins and asked me how to make it stop. The messages said to send STOP to unsubscribe so we did that.

But we just received another 12 messages from a different one today so mum's really freaking out now.

She's called Telstra and they said they can't do anything coz its a 3rd party thing, and that there's another $108 of charges on there now. She's tried to call the number from the people sending the texts but only getting a machine telling her to leave a message.

Hopefully she's learnt a lesson in not signing up to things without knowing what it is. But is there any way to dispute these charges? The phone bill shows the company as having an ABN number, so i guess that means they are an entity in Australia and subject to Australian consumer law. The website I posted above in the fine print say they'll only send 3 messages per week, they've obviously broken that with 12 in 5 minutes so maybe there's legal grounds there to object. But who do we contact if we can't resolve it with the company in question??

Any suggestions?

Here's the Information i got from the phone bill and TXTs:
Provider: DIALOGUE COMMUNICATIONS Pty Ltd
ABN: 55 108 346 854
Contact: 1300 886 232 (Champions-Quiz)
Contact: 1300 309 775 (GrandPrizeQuiz.com)

EDIT: Found this: http://forums.whirlpool.net.au/archive/1935978
Looks promising!