EVERY SMALL BUSINESS wants its customers to be happy. But what happens when a relationship with an important client becomes strained?

"It's just stressful," says Melia Lyerly, co-founder of the Lyerly Agency, a Charlotte, N.C., marketing, advertising and public-relations firm that has relied on repeat business and referrals for its success over the past 30 years. When breakdowns with clients occur, it's usually the result of miscommunication — and these days, email is often to blame. Details about a project might be misunderstood; even a joking comment can be misinterpreted. When that happens, "I will lose sleep about it," Lyerly says. "Our job is to get in there and get it resolved as quickly as possible."

Of course, client relationships can become strained for a host of reasons: a failure to communicate, as in Lyerly's case, an honest mistake or unmet expectations. But all is not lost. Here are some ways to repair the relationship:

Meet face-to-face. Despite technological advances, an in-person meeting is still the best way to communicate — and the best method for smoothing over disputes. Get in the car or hop on a plane if necessary. Also, if it's a lower-level employee or salesperson who's on rocky ground with an important client, the business owner (or someone high in the company's organization) should attend the meeting — the extra attention goes a long way.

Do the right thing. If it's something you did, apologize. Even if it's not your fault, don't waste time arguing about what happened. Come up with a way to fix the problem — and do it for free or at a discounted rate. Bob Miglani, the New York-based author of "Treat Your Customers," a book about running a Dairy Queen for 20 years, recommends the "always replace a dropped cone" approach. Sure, you sacrifice short-term revenue by giving away a product or service, but "you're earning that customer for life," he says. That's especially wise in a tough economy, when losing customers can be especially painful to the bottom line.

Let them vent. Give angry or frustrated clients an opportunity to express their grievances, says Craig Cortello, a veteran salesman who now heads New Orleans consulting firm Fuzzy Widget Sales Solutions. Cortello says he's salvaged many relationships this way — even with clients who swore they'd never work with him again. A client who vents long enough sometimes reveals that extenuating circumstances — his or her company's financial problems, for instance — aggravated the problem. "When they start getting everything out — sometimes, it's just the situation they're in," Cortello says. "It's sometimes not all our fault."

Give them time. Disgruntled clients might not be ready to repair the relationship quite yet. Check back with them in a few weeks — or even a few months — to see if they are ready to talk. In the meantime, keep them on your marketing mailing list (either snail mail or email) so that your company still stays front of mind, recommends Barry J. Moltz, a business consultant and author of "Bounce," a book about entrepreneurial success.

Call it off. Bad customers can drain profits, and there are times when you're better off without them. "Try to go through and assess the value of your customer relationship," suggests Curtis N. Bingham, president of Predictive Consulting Group in Boston. Figure out how much it costs you to serve that client, and how much in revenues you make from them. If it's one of your more lucrative relationships, "do whatever it takes to repair the problem — grovel as long and as hard as possible," he recommends. But if it's costing a lot to maintain the relationship, and you're not seeing any profits, then think about ending it. "Maybe it makes sense to let them take their marbles and go home," he says.

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