At the time, it seemed the best course of action, given Comcast's sterling reputation on the social-media service.

But Comcast ignored him, pushing Harper, a 26-year-old digital-media strategist in Naples, Fla., to take extreme measures. He began a campaign of "flaming" Comcast with withering tweets.

Eventually, he got Comcast's attention, and the issue was resolved.

Leyl Master Black had quite a different experience. Instead of looking for a Dell rep after her PC's hard drive died, Black got the rep to come to her.

After Black griped on Twitter, a blogger friend put Black in touch with a Dell expert. Problem solved. "It was so quick," says Black, 39, of San Francisco.

Such are the vagaries of customer support on Twitter. Hailed as the Next Big Thing, customer service through tweets is a work in progress, says Pete Blackshaw, executive vice president of digital strategic services at Nielsen. The performance of many companies has been uneven as they try to handle a crush of customer queries, integrate Twitter into their overall strategy and manage the heightened expectations of consumers.

"Social media is not a panacea," says Blackshaw. "It is a catalyst for fresh thinking on how companies can improve customer service in the digital age."

More than half of the Fortune 100 companies are using Twitter for customer service, recruiting employees, blasting news and announcing promotions, according to the study by public relations firm Burson-Marsteller and its digital-media unit, Proof. Yet a recent Deloitte survey concludes that organizations continue to struggle to harness social media's full potential.

The 'instant gratification' trap

"Companies go in with expectations too high, and they risk disappointing customers who don't get prompt replies," says Lloyd Trufelman, president of Trylon SMR, a public relations firm for media companies.

Twitter should augment customer service, not be some magic bullet, he says. "If a company's DNA is not truly dedicated to listening and responding to customers in a genuine and timely manner, no technology will provide a solution."

Michael Brito, who left Intel as director of social media this month to take a similar job at Edelman Digital, acknowledges it is "impossible to respond to everyone on the social Web unless you have an army of thousands of people on your staff."

There is also the misperception among many Twitter users that they have higher priority for help.

"Twitter is like a tragically hip New York night club," says Bob Warfield, CEO of Helpstream, which provides customer service technology to companies. "It is a cool, easy way for companies to engage customers in social media. But the experience can be loud and crowded."

Companies are spending millions of dollars on their Twitter operations, a fraction of the multibillion-dollar customer service industry.

Consumers certainly are looking for help on Twitter. In one recent survey, 58% of respondents said if they had tweeted about a bad experience, they would like the company to respond to their comment.

Easier said than done, customer service experts say.

There are simply not enough resources to handle the avalanche of tweets, says Jason Mittelstaedt, chief marketing officer at RightNow Technologies, a provider of customer service software that oversaw the survey.

That's especially true, he and others say, when so many consumers use the Internet day and night, expecting immediate results. "They want instant gratification," Mittelstaedt says.

Often, results depend on the scope of the problem, the availability of support staff online and the time of day. Getting a prompt answer at 3 a.m. isn't likely.

"Twitter is not perfect, but there are a lot of benefits that outweigh some of these hiccups," says Frank Eliason, director of digital care at Comcast. Above all, Twitter has made Comcast "more transparent and showed the benefits of listening to our customers through all communications channels."

He has 11 people working under him to handle queries from 33,500 followers. He points out that Comcast uses Facebook, YouTube, blogs and help forums in addition to Twitter.

"Solving a technical issue in 140 characters is hard," says Toby Richards, head of Microsoft's community and online support. Its @MicrosoftHelps, devoted to Windows 7, has 3,500 followers. There are plans to beef up support for non-Windows 7 products as well.

"It's like being a high-tech concierge," he says of @MicrosoftHelps' seven full-time employees and much larger support staff. "Our tweets have links to solutions. The essence is for followers to help one another."

Ideally, Twitter should be one of several solutions. A small and manageable operation smartly augments strong phone, e-mail and online chat support, says Rich Buchanan, chief marketing officer at home phone service Ooma. Its five-person team serves about 1,000 followers.

With such a large ratio of Twitter followers to company reps, it is likely the customer service experiences of consumers will continue to run hot and cold, Nielsen's Blackshawsays.

"Twitter is raising the bar, but anyone who oversells it is succumbing to digital hype."

Enlarge By Eileen Blass, USA TODAY Frank Eliason, director of digital care at Comcast, says Comcast uses Twitter, Facebook, YouTube, blogs and help forums to help customers.