I suffer very bad heartburn when I eat normally and it's completely disappeared since I've been on LT. I can only guess it's down to the stomach producing less acid, as I'm eating less. I get a hint of it though when I have a flapjack late at night, say around 9pm and then go to bed.
As for your complaint, your stomach should be producing less acid cause it's getting less food so maybe you should mention it to your parmacist, as you could have an ulcer - not being dramatic or anything but it's better be safe than sorry.