I really can't add much more advice to MHN's great start - its everything I would suggest. Its a bad idea to let a dog off lead if they don't respond to "come" EVERY time you give the command - who knows (as it sounds like you've found) where they'll jet off to?!
In addition to lead work on the recall command, you can invest in fences or a collar as you were thinking, but I would suggest only using it on your property in training mode - not as a way to keep them on the property without training with the two of them.
You could also look into exercise lead lines - basically zip lines you hook your dogs collar to so they can run across the yard, but are still tethered to something and can't run off. You can use these for unsupervised play AND for training on recall.
As MHN said, never chase a dog who's run off - turn the opposite direction and make a "game" of them chasing you back. Always reward a good response to "come" or any command while you're working with them.
It may take some time, but I know your dogs will get the hang of it, even the older one. Please keep us posted as to how things are going, and good luck!