Just wondering what options are there available flying to Vietnam other than Vietnam Airlines and wishing to fly through all in same day without having to overnight in Singapore or Kuala Lumpur

Try Cathay Pacific or Royal Brunei to see if they can connect direct.
Royal Brunei often has good deals . Check this site out to see if they have any specials:

www.bestflights.com.au

There are also lots of other national and budget carriers that list their prices there.

We got a flight with Garuda