I am studying in australia as an international student from Bangladesh, female 21 years old. i am doing?

digital media certificate IV course here. its one year course. and my visa will be expired on 30 AUGUST 2010. i cant extend my visa. but i have to study more. i want to have DIPLOMA AND BACHELOR degree on same field here in AUSTRALIA. so how can i do that? i am so worried. any help would be appreciated. thanks in advance