Sorry to hear about the babies with colic. Have you ladies tried the different ways to burp?
1, over the shoulder,
2, sat upright on knee patting and moving you hand in a clockwise direction on the back.
3, baby sat on your knee place your hands to support his head, and move his whole top half in a circular motion
4, place baby on there front on your knees and raises their bum, also massage the lower back
I also use infacol, and find that helps a lot but only for the top end. A friend recommended powered cucumber, Not tired that yet.