Hi @skyesheppard,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
You've tried some pretty strong chemicals without any luck which makes me suspect the "stain" is not really a stain, it's actually the top layer of white pigment being removed to reveal a yellowed layer beneath.
Bleach removes colour by oxidizing the pigment molecules that give materials their colour. This process breaks down the pigment’s molecular structure, rendering the material colourless or lighter. Unfortunately, this is not reversible as the pigment has essentially been destroyed.
To fix the problem, you will have to either paint the benchtop or replace it.
The Dulux Renovations Range of paints, which can be used to paint the countertop back to white is likely a good option.
Check out How To Paint A Kitchen Benchtop With Dulux for some guidance.
Alternatively, you can check out our range of benchtops as potential replacements.
Let me know if you have any further questions.
Jacob
