Looking for coffee roasters that sell Robusta beans

I have been to Indonesia a few times and will likely visit again in the future. The last few times I was there, I was unable to find coffee to my liking at the cafes I visited in Bali and Surabaya. I love dark roast with low acidity (pretty much like Singaporean coffee at the Kopitiam). All the cafes I visited mostly served Arabica with light to medium roast. The only Robusta I could find tasted very strange, like it was still green or something. I bought some ground coffee from a "coffee factory" in Singapore that tastes absolutely delicious. The owner told me the coffee beans are Robusta from Indonesia! So, where can I find coffee roasters that have Robusta beans (dark roast) in Denpasar or Surabaya? I would like to buy whole beans or ground coffee to take with me abroad the next time I am there.