I agree that bindweed is a total pain, and I have it among my raspberries. In the spring I dig out as much of the root as possible, then as previously advised, when it inevitably rears its head again, I go along at the base of the raspberries and cut it off at ground level, leaving the winding stems in place so that I don't damage the raspberries. I also don't use weedkiller, but each to his own, and someone else may be able to advise you differently. We all have to garden in the way that suits us best according to our time and physical abilities.