Do not book with Webjet. They are a fraudulent operation. I canncelled my wifes ticket 3 weeks prior to the flight and requested the taxes portion of the ticket. Webjet refused. Airlines will refund the tax portion if a flight is not taken as the tax is not paid to goverments until the flight is taken. As a result of Webjet refusing to refund the taxes they can pocket the money as additional profit.
Reserved seats?: Lately, some bargain airlines started selling "reserved seats" on the plane. However, the seats are all quite similar and even if you don't reserve a seat when you book your ticket you will still be able to choose your seat when you board the plane or you will be assigned one at the check in desk. So you can easily avoid paying extra money in order to reserve your seat.