Aregular Amazon customer, Yvette Thompson has found shopping online to be mostly convenient and trouble-free. But last month, after ordering two CDs on Amazon.com, the Silver Spring reader discovered on her bank statement that she was double-charged for the $26.98 order. And there was a $25 charge that was a mystery.

Thompson clicked through the Web site to find the customer service e-mail form to contact Amazon. When she didn't receive a reply after three days, she sent another. And another. She has copies of the four e-mails she sent over two weeks. When she couldn't find a customer service phone number on Amazon.com to request a refund, she got more frustrated.

"These e-mails are supposed to be responded to within 24 hours, yet I have not received anything," she says, referring to Amazon's customer response policy. "I haven't been able to get any information from Amazon.com."

One general complaint that has plagued the online shopping industry for years is slow or inaccessible customer service. A survey released earlier this year by ForeSee Results, a firm that studies customer satisfaction in various industries, found that "availability of help with questions and problems while ordering" was the lowest rated of 16 factors that make online customers satisfied.

Typically, to reduce steep call-center costs, online retailers steer customers toward solving their own problems by having them click around the Web site for FAQs or e-mail their complaints, the ForeSee report states. "But customers clearly find that most existing methods of online help are inadequate -- and give it a barely passing grade."

In its nine years, however, Amazon.com has set high standards for innovative Internet retailing practices. Vividence, a market-research firm, ranked Amazon first for "overall customer experience" in August. Barnes & Noble, Circuit City, eBay and Lands' End completed the top five.

Told of Thompson's problem, Patty Smith, Amazon's director of corporate communications, immediately investigated. She found that each of Thompson's four e-mails had been answered within minutes after they were received. "Apparently she never received them," says Smith, speculating that Thompson's spam filter may have blocked the replies.

Because of a technical glitch, says Smith, Amazon did charge Thompson's debit card twice, so $26.98 was being refunded.

The mystery $25 charge? Smith says that if it was an overdraft penalty from Thompson's bank because of the double-billing, Amazon would reimburse her.

Cathy Ceely, a member of Amazon's executive customer relations team, phoned Thompson to explain that the Web site's tech division was looking into why the e-mail replies weren't delivered. And, "as a gesture of goodwill and in apology," she e-mailed Thompson a $20 gift certificate toward her next purchase.

Thompson says she's satisfied with "how well they handled this issue" and will continue shopping at Amazon.com, but she would prefer that Amazon post a customer service phone number or street address on its Web site.

Smith says the majority of customer questions are resolved with the on-site features such as the "Where's My Stuff?" button or the e-mail form. "Most customers don't need to call customer service, so we don't have it on the site for that reason," she says.

But, she adds, when all else fails, "Amazon's phone number is listed with the 800 directory" -- a compilation of all toll-free phone numbers (see below).

Got questions? A consumer complaint? A helpful tip? E-mail details to oldenburgd@washpost.com or write Don Oldenburg, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.