Weren’t at least a couple of independents supposedly “conservative” when they were elected and then betrayed their constituents to support Labor?
More or less.
There were four independents elected in 2010 - Andrew Wilkie of Tasmania was never likely to support a conservative coalition government (he first came to public attention as an so-called 'whistleblower' from Australian intelligence opposed to the war in Iraq) and so his support of Labor was unsurprising, and I believe an honest stance given his political beliefs (he has just recently announced he will no longer support the government because Julia Gillard has broken a promise made to him about Poker Machines).
Bob Katter (of Queensland) was once a National MP (and member of the conservative coalition) but left the party in 2001 over some policy disagreements. He remains a conservative though, and there was never any real question of him supporting a Labor government. He would have supported the coalition to give them government but as his one seat didn't wind up making that difference, he isn't formally part of any group - except a new party forming around him which hopes to win a number of state seats in this years Queensland election. Again, he's an honest man.
This left Rob Oakeshott, and Tony Windsor, both of NSW. Like Katter, both Oakeshott and Windsor were once both Nationals and both describe themselves as conservatives and both were elected into Parliament in 2010 because of preferences from the conservative parties. In simple terms, about 2/3rds of votes in their electorates were cast for conservative candidates - but they chose to support Labor.
Whether it's a betrayal depends on your point of view. They would argue that they took advantage of a once in a lifetime chance to force a government to give their electorates what they wanted, and Gillard was willing to give them things, that Abott would not. And, in fairness, there's some truth to that. But they did give us a Labor government with all that entails as well. Personally, I've got more time for Oakeshott than for Windsor. I think Windsor decided he was going to support Labor and that meant Labor would have 75 seats regardless. At that point, Oakeshott going to the coalition would have made it a truly hung Parliament of 75-75, which meant only Labor could possibly form a government and so he went to them in the interests of stable government. I can respect that to some extent.