I would like to share my success story with reversing heartburn/acidity with yoga. I had tried asanas and pranayama/meditation they had helped to a large extent. But i would get it back if i forgot to do them for 2-3 days. I learnt a yogic practise called kunjal from Swami Satyananda yoga school (Satyananda is a disciple of Swami Sivananda)
This is called kunjal. It involves drinking 6-7 glasses of drinking warm salty water and throwing it out early in the morning on empty stomach. It produces amazing results in short time. Initially, you need to do it frequently. After that, the frequency can be reduced to once or twice per week. It has produced amazing results for me.
More details can be found from yoga teacher or a website at http://www.theholisticcare.com/asana/Kunjal%20Kriya.htm.
If you've any special health condition, do it under expert supervision since you will need to drink salty water (although it will be thrown out on completion). The biggest obstacle for this is the human tendency to hate throwing out.