Former Home and Away star Pia Miller absolutely spoiled her son Isaiah for his 18th birthday this weekend.The Chilean-Australian Bondi model, 37, who is engaged to Hollywood agent Patrick Whitesell, 56, went all out for her son Isaiah’s 18th - even hiring a private jet for him and his friends.According to the Daily Telegraph, Miller may have spent up to $25,000 for the short luxury fare that carried Izzy and his pals from Sydney to Melbourne. The birthday bonanza was then held at the rooftop bar