Hi @sarah-v19,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Can you see a model number or name somewhere on the cistern? It can often be written on the inside of the cistern or indented in the plastic of the cistern. Knowing the specific model will help us to track down a compatible part for your toilet.
This FIX-A-LOO Thunderflush Dual Flush Cistern Outlet Valve suits Caroma cisterns with buttons at the front of centre position and looks like it could be an option. Still, we'd have to confirm compatibility with your specific cistern.
Check out my colleague @MitchellMc's advice in How do I remove the flush valve? This looks to be very similar to your cistern and is definitely worth a read.
If you can do some investigation for me and let me know what you find, I'm happy to confirm the compatibility and advise further.
Let me know how you go.
Jacob
