I've been in exactly your situation (chest pain, A&E, reflux, Gaviscon, go see your GP, plus further investigations). IME too much Gaviscon can cause digestive upset that may feel similar to reflux. Try to stick to no more than 3-4 doses per day. I find the liquid far more soothing than the tablets.
Try taking Ranitidine once a day, increasing to twice daily if necessary. But you can't take ranitidine and antacids within 2h of each other, as the antacid would affect the ranitidine.
Try Rennies as well. I find that I can eat huge numbers of Rennies without causing any upset to my stomach.
Have a look at what you're eating. I find that wheat makes my reflux worse. If I have irritation from ongoing reflux, then hot drinks, chilli and alcohol cause the pain to flare up and worsen. I also need to eat less at a time, ie not to fullness, and to drink before meals and between meals, rather than after meals.
Hope some of this is useful for you.