Check that Telstra don't charge you termination fees etc.
What have they said or done to fix the issue.
It took four tech visits and many phone calls - last one lasting 80 mins before I could get a fast, stable internet ADSL2 and phone connection. Two occassions - no phone, nada, dead silence. Other times if I used phone I would lose internet connections.
They may be doing this to give you a stable but slow connection. Due to NBN they are loath to fix corroded copper cabling yet still offer the service.
Their DIY trouble shooting pages are also a joke. Even with no javascript, all I get is error messages about page not found or a white page.
Good luck and you will need a lot of bloody minded determination.