Until a few decades ago, many American business firms operated under the policy, "The customer is always right."

Entire families often dealt with the same stores for decades because merchants thought it was important to cater to old customers. In those days, the customer was king.

But, alas! The king is dead. He was killed off by prosperity. Customers are a dime a dozen now, and there is widespread unconcern for the customer, his patronage or his feelings.

Let me cite you some examples taken from just one day's mail:

Alvin R. Myers Jr. of Clinton has for 30 years been a customer of what is now the Clinton branch of Equitable Trust Co. He has both checking and savings accounts there. Also Visa and MasterCard accounts.

Six months ago, he bought a money market certificate from the bank. When it matured, Myers decided not to renew it and asked for a check.

The bank informed his there would be a charge of $2.50 for the check. "It's a new policy," a clerk explained. Myers considers it unfair for the bank to charge him $2.50 for paying him what it owes him, and I'm inclined to agree.

An unhappy Bethesda man bought four Goodyear Tiempo tires from Market Tire. When one tire developed a menacing bulge, he returned to Market Tire, where he was told no adjustment could be made because he had obviously "struck a curb or something real hard" and damaged the tire. If he wanted to pursue the matter, he could go to Goodyear and see if they would do anything for him.

So he went to Goodyear where a manager examined the tire and said, "Well, it doesn't appear that you caused the damage by hitting something because the rim doesn't show any sign of impact, so I'll make an adjustment for you."

The Bethesda man's unhappiness is explained in these words: "The manager based his adjustment on a much higher 'list' price than I had paid Market Tire. So the amount I had to pay him for a replacement tire was only about $5 less than the full price being charged for the same tire in other stores -- without any adjustments. Some guarantee."

For the past six years, N.L. K. has been receiving from 20 to 60 annoying telephone calls a day. N.L.K. writes, "We have changed our number four times and have repeatedly asked the telephone company to trace the calls, all to no avail. They tell us the calls are coming from an exchange to which they cannot trace calls because of 'old wiring.'

"Two years ago, I read a magazine article about a little black box that can trace any call, and I have since read substantiation elsewhere. But when I ask a telephone company spokesman about this, I get vague, unsatisfactory replies.

"It is frustrating to watch telephone company commercials boasting of the technological miracles that make Bell System service so wonderful when we are being harassed by so many calls that the company says it can't trace.

"Incidentally, have you ever tried to reach the annoying call division? Try it -- if you like to dial a lot. We think the phone company is doing a shabby job on service and protection."

If Ma Bell would like to make a more diligent attempt to trace these calls, I will be glad to identify N.L.K. to any interested C&P executive. c

Dorothy Mills of Arlington reports that on Tuesday of last week she found in her mailbox 23 letters addressed to a dozen people whose names and addresses in no way resembled hers. When she turned over the letters to the post office, they were "received with a blank stare and no explanation."

Dorothy didn't expect anything better. A few weeks before, she mailed an insured package at the same post office. The next day, it was delivered to her !

Dorothy took it back to the post office and pointed out that the package was supposed to go to the addressee, not to her. A clerk took the package from her and headed for a back room, explaining, "I'll find out if you have to pay postage on it again."

Let me file this minority report: When a command button on my 2-year-old digital electronic watch became inoperative, I took the watch back to Chafitz. It was repaired while I waited, no charge. Nobody asked my name, nobody asked whether the watch was still under warranty, nobody gave me a hard time.

I couldn't believe it.