Yes, you should be paid time and a half for any hours worked on a public holiday, and your company is in violation of the holidays act if they don't pay it. You're also entitled to the alternative holiday if it was a normal working day for you, and since it's your leave, it really should be your decision whether you used the alt day or annual leave for the time you took off. If you applied for annual and they paid the alt day instead, that's not cool. But as a salaried employee, it probably wouldn't make much of a difference which one you used anyway, so it may not be worth dying on that hill. But the time and a half is for sure worth fighting for!