New research from customer relationship management leader Convergys Corporation (NYSE: CVG) shows that while most consumers hold U.S. customer service in high regard, those who are dissatisfied with their service experiences are becoming increasingly vocal.

According to findings from the 2011 Convergys U.S. Customer Scorecard Research, the percent of U.S. consumers who report a bad service experience to the offending company continues to rise, up 5% in the past year and up 13% since 2009.

At the head of the list of complaints over service: customer effort. One-third of survey respondents said it takes at least a moderate amount of effort to interact with U.S. companies. Among the minority who describe themselves not satisfied with customer service, U.S. consumers complain that it can take two, and sometimes three or more, attempts at interacting with a company to resolve a problem.

“Clearly, ‘effort’ is the flashpoint of the service experience, and those companies who make problem resolution hard for customers can pay a stiff price,” said Igor Sarenac, Convergys vice president. “Although small in number compared to the mass of U.S. consumers who gave high marks to service in the research, greater vocalization by a handful of dissatisfied consumers can do considerable damage to a company’s reputation, leading to a drop in consumer purchases, reduced advocacy, and new customer avoidance.”

The 2011 Convergys U.S. Customer Scorecard Research also finds that 8 out of 10 U.S. consumers who have had a bad service experience tell their friends or colleagues, often using social media and other new communications technologies. Over 6 in 10 U.S. respondents to the Convergys survey have Facebook or Twitter accounts or their own blog, while 4 in 10 own smart phones or other mobile devices/tablets with data plans.

Negative social media posts can result in lost business. Responses to Convergys’ U.S. Customer Scorecard research show more than 1 in 4 U.S. consumers read about someone else’s bad service experience, and more than 7 out of 10 who read these posts were influenced to avoid or stop doing business with a company. The Convergys research also shows Millennials are more likely than other generations to share their bad service experiences via social media or texting.

“If customer effort is analyzed and proactively reduced, companies can increase long-term loyalty and turn customer relationship management into a revenue generator rather than a cost center, said Sarenac. “Companies don’t have to spend more money to increase customer satisfaction. They just need to focus on solving customer issues the first time issues are raised, ensuring they – and their customers — expend the least effort possible.”

In the coming weeks Convergys will release further findings from its 2011 U.S. Customer Scorecard Research on channel management and personalization.