One of my mentors is big on the idea of starting your strategy with a consideration of the entire customer experience, from the moment someone first hears about your company until the moment you file the completed project documentation. What happens at each point along the way? What happens next? What reaction are we trying to drive? What will we do when we get said reaction? Then drill down into tactics from there.
The situation you describe isn't just a marketing/sales problem -- it happens everywhere. It happens when the people tasked with execution say, "Sales promised WHAT?" It happens when you get stuffed-up invoices that don't relate to either what was promised or what was delivered. And every time it happens, we need to learn from it.