Get on the phone and say ombudsman... They might do something before you even have to call the TIO. I've had Telstra issues and when I've said I'm contacting the ombudsman they've fixed the problem there and then.
I've cancelled two contracts via the TIO. One with crazy johns and one for an Internet thingy with Vodafone. It was actually kinda easy.
Good luck. Hope you manage to sort it out.