Wrong Flight Details

I booked two flights with Jetstar, I signed up to their club and accidentally put both bookings under the same name.
When calling to change I was met with a $242.00 AUD Charge. I looked up the cost of a new flight it was $151.00.
I called and asked to speak with the complaint team which is conveniently online. It took the service officer about 5 minutes to reply to me each time and when they did they just kept referring me to the terms and conditions.
I advised that they are going to waste a seat and they suggested I take both flights. I am not two people how is this possible I asked. The officer replied with "okay well it is $242.00 to change the name."
In the end I unsubscribed from their Jetstar Club and will never fly with them again.