If there's a hardware problem afoot only a replacement fixes it.
But - I'm reminded of the bad rap the HTC One M7 camera got for having a purple tint (torches and pitchforks, bad news!) but everyone that professionally reviewed the problem associated it with low light - and one photographer explained it in terms of sensor physics.
So I'm wondering - what if it's not a hardware problem but more an issue of the hardware/software interface right at the edge of tolerances?
After all, on paper, the S6 ffc is kind of very similar to the HTC One M7 main camera - and - low light and something purple.
Check out "FreeDCam"
https://play.google.com/store/apps/details?id=troop.com.freedcam
I've spent a LOT of time with the devs of that app, they're insanely pro and I've learned a lot.
Especially that the ability to take a picture super quick, especially in low light, is not our friend. The main processor gets priority over the image processor and the image engine doesn't get enough time to do its full job.
That app will help you control that.
Here are some of the dev team's recommended settings for best quality -
Anyway, I don't have an S6 so I could be full of beans but that app is free to try.
And it's packed with great camera features.
Including getting your best setup, saving it, and then just going point and shoot as user from there but with better than point and shoot results.
Hope this helps, let me know.