Many years ago - in fact, it was back in the last century - a customer service manager said to me,
"Sales sells the first one, and Customer Service sells every one after that."
He said it because he felt like his team of Customer Service people were unsung heros in the company. The company experienced significant growth in the 90's, and the sales people were lauded as the engine for growth. They drove the nice cars, went on the extravagent incentive trips, and were constantly recognized in company-wide emails from the president (who himself, had risen up through the sales ranks).
Sales got the applause for brining in the new customers, while a team of faceless Customer Service reps worked tirelessly in the engine room, keeping those customers happy, and buying again and again, long after the sales people had moved on.
That was long before anyone coined the term "social media."
15 years later, things aren't so quiet anymore in the Customer Service engine room. Today, customers will openly tell the free world all about the Customer Service Experience they had five minutes ago; they'll reach more potential customers, and impact a brand's reputation in less time than it takes to call a meeting of the marketing team. Sales can still sell first one, but more often, it's the wildfire reputation of sensational Customer Service that ignites the interest of the new customer.
Given our hyper-sensitivity as customers; a sensitivity to both good service and bad service, and our willingness and ability to share our feelings with the entire world in just a couple keystrokes, good customer service absolutely, positively should be treated as a marketing tool.
I certainly hope that the Customer Service Manager from the 1990's has kept at it long enough to finally get his due credit - from the social recognition of thousands of vocal customers.