Unlimited Voip Calls Within Australia, Mobile, National and Local Calls, No Catches?

Hi everyone. Im hoping someone can help me with this one. I live in Australia, and want to use voip soft phone to make my calls online, anywhere in Australia. Unlimited mobile calls, national and local calls. But we dont want any catches to the account. We are already with a company which we have gone over our limited easily, and they could cut us off anytime. It is under the fair use policy. They said we cant go over 100 mobile calls per month, 300 local, 300 national. we have made so many calls to mobiles, which i think we will be disconnected. Is there any company that offers no restrictions, and you only pay a cap amount $$$ every month, no more to pay? thanks.