We are renting a property in south australia, we found out that the owners are going to sell it, we are locked into a fixed 6 month lease, what are our rights

I'm sorry you haven't received an answer in 3 days. You need help with AU tenant law specifically, and can probably get a quick answer for free from a local attorney. Hopefully the owners mean they plan to put it on the market, not sell it out from under you? Do you have the full 6 months left?

Not sure if this applies in Australia too but in the USA the lease remains valid until its normal end. The new owner can give you a 30 day notice a month before the lease ends saying he will not renew and you must move. Otherwise you have 6 months to sit right where you are, unless this is a bank foreclosure

AU law is based on British common law same as the US. So I would suspect its similar. A lease is a contract. A sale of property does not affect an existing lease. The new owners will have to honor the lease, but are not required to renew it.