i had acne too, but used
Isotretinoin - Wikipedia, the free encyclopedia and it worked wonders
i know you're looking for natural stuff, but if it ends not working out, use isotretinoin, it ends with all the acne in no time for as long as you are taking the pills, and after you've been taking it for 1-2 years (depending on your dosage) you can stop taking the pills and the acne will never be back anymore.
btw, i had severe acne, so just cleaning my face 3 times a day and not eating junky food & chocolate didnt work