Yes, they do reseed all over the place. I've also had problems with both seed packs (local name brand) and potted plants at nurseries not being the labeled variety.

I've planted two packets and four starts in five years none of them has been Heavenly Blue!

I find the seedlings easy to pull up and I most likely will try them again. I don't find them horribly invasive.

Field Bindweed, the white perennial weed here is horribly invasive. I've been spraying my neighbor's with Round Up for years and it laughs at me and continues to come up on my side of the fence.

You may be confusing corn bindweed, also called field bindweed (Convolvulus arvensis) with giant morning-glory (Calystegia silvatica). Both are common, but the Convolvulus produces pink or white flowers less than 2 inches across. Anyway, try spraying when flowers appear (see label directions) but not before. With glyphosate the top of a plant has to be big enough to pick up enough of the spray to kill all the roots. Even then persistent perennial weeds may require repeated assaults. With some weed patches there may also be dormant seeds in the soil that sprout after the existing plants are cleared away.