Taxis are controlled at MNL airport. Go to the taxi kiosk, tell the agent where you want to go, the agent will give you the price & you'll get a ticket to give the driver.
The prices are fixed. 330p to the Dusit may not be right. I suspect it'll be more like 450p. Pay the driver exactly that and no more (though a 10% tip will be appreciated.)
I've never had any issue with taxis from the airport. Taxis within MNL are an entirely different story. Some will refuse to turn on the meter. Just get out & find another.