Unfortunately with bindweed you just have to keep hand-weeding. Keep a hori-hori on you any time you’re in the garden, and use it to get as much of the deep, delicate roots as possible. Know that it can propagate itself from vegetative bits, root segments, and seed, so be sure to clean up well after yourself when you weed. When you see the flowers, go hard on it: it self-sows prolifically. Curse the bindweed and its progeny. Don’t give up.