Congratulations on the troubleshooting, that was very smart work.
Normally the LEC ties their lightening protections to a cold water pipe or a copper coated steel rod driven at least six feet in the ground.
Maybe the tech doesn't really know what he can do, as in doesn't want to be bothered to do. If there is a cold water pipe nearby, there is no reason you couldn't run a large gauge copper wire, at least as big as the current ground, to the cold water pipe and use a proper grounding clamp. That would be at least as good as anything AT&T puts in.
