This. Nothing like a lawsuit to get a company to actually respond; even if they win it, the cost of sending someone to address it is almost guaranteed to be more than if they just settled the issue.
Besides that, if you threaten to sue, you're just giving them time to construct a defense strategy instead of addressing the actual issue at hand. With the threat, the burden is still on you to take action. With an actual lawsuit, they must act within a certain interval, or you win by default.
