Chanca Piedra is also known as "stone breaker." I've heard finding good herbal remedies is getting harder in Australia. Can you order online?
As far as malic acid, drinking 16 to 32 ounces of UNsweetened apple juice every day for a couple of weeks works fine for me. Just avoid the stuff with additives and sweeteners; look for plain organic juice if possible.
I'll be doing an apple fast next week. For 3 days, you eat NOTHING but apples (and drink only water), but you can have as many apples as you want. At the end, I'll follow with a liver flush. The last time I did that, the Liver Flush was VERY good and when it was all done I felt FANTASTIC! Of course, DURING the actual fast, the detox load was something else!