Have you ever been tested for h-pylori? Maybe there is an underlying parasitic issue causing the high acid.
magnesium and/or potassium ascorbate would be good choices to try, you just need to make sure that you dont get too much potassium or magnesium though. The main thing is that at vit C doses high enough to have a profound affect on heart disease using a calcium bound product will cause problems over time due to too much calcium intake.