Consumers complained more about mail-order firms last year than any other business, according to a survey by the National Council of Better Business Bureaus.

Mail-order firms generated nearly one out of every five complaints handled by the nation's 168 local Better Business Bureaus -- more than double the complaints about any other businesses.

"They've ranked at the top of our annual survey since 1975," said Allen L. Beatty, vice president of bureau affairs at the National Council of Better Business Bureaus. "It's partly the volume of activity in that field, and partly because with orders going in through the mail and products coming back through the mail there is a lot of opportunity for things to go awry."

Home remodeling and improvement firms followed in second place, receiving 8.4 percent of the of the 2.1 million complaints last year.

Other businesses that raised the ire of Americans were, in order, franchised auto dealers, home furnishing stores, auto repair shops, direct sales firms, miscellaneous auto product sales, department stores, dry cleaners and television repair shops.

Used car dealers, who have been criticized by consumer groups in the past, were ranked 17th on the list, with less than 1 percent of the consumer complaints.

Nursing homes, with a settlement rate of about 90 percent, had the best record of settling consumer's problems, while general membership and lobbying groups were least likely to settle complaints, the business group said.

Of the 6 million calls to Better Business Bureaus to inquire about goods or services, about 16 percent concerned home repair and improvement companies, the consumer complaint study said.

Most of these calls were from homeowners inquiring about the reputation of a company before having work done. Mail-order sales ranked second on the inquiries list, generating 6.3 percent of the calls in that category. Not far behind were queries about insurance and franchised auto dealers.

Rounding out the the 10 most inquired about businesses were organizations soliciting donations, vacation certificates companies, direct sales firms, work-at-home businesses, heating and air conditioning firms and auto repair shops.

Unsatisfactory service was the most common complaint to the Better Business Bureaus, accounting for 23 percent of all unhappy consumers. Late or damaged delivery was second at 17.3 percent, followed by unsatisfactory repairs, 14.9 percent; credit or billing problems, 11.2 percent and product quality, 9.6 percent.

Consumers also complained about warranty problems, failure to provide refunds, selling practices, advertising practices and discontinued businesses.