You may want to try a firmware update first, it may rewrite the TV's operating firmware and restore operation of the color bar control. This website has the instructions, and the USB software you download and load onto a USB stick,then install it on your TV set following the instructions.
If your color control still doesn't work, then it looks like you have to remove your old main board and replace it.
Here's a site that sells it.
You see the BNxx-xxxxx number listed in the page. That's your actual part number found on that board on a sticker.
I always get the board's number directly off the sticker and Google it for the correct part and price.
Try the software first, and if that doesn't work, lay the TV face down on a pad, remove all the screws on the rear cover, lift it off, and look for stickers on that main board with the BN number. All Samsung boards start with that BN number.
Any questions? Use the reply button for answers. BTW, you're in Australia, I'm in the USA. There will be a time delay since we are on different continents.