Automatic bill payment. Paperless billing. Easy and secure online transaction.

They make it sound so easy — until it gets so hard.

Not that I’m bitter about spending last Saturday trying to change the Visa number our family has on file with various vendors.

I’m guessing millions of Americans already have done this — or soon will.

You sign up online for “auto-pay” and the next thing you know, someone has stolen your credit-card number, so you have to alert all your auto-payees that you have a new number and the old number doesn’t work anymore.

Trouble is, no two vendors have the same system for changing those numbers. Their websites, in fact, are laid out willy-nilly as though nobody ever has to change his or her billing info.

Misery loves company, and apparently I’ve got lots. According to something called the Identity Theft Resource Center, there have been 606 “data breaches” just this year across the U.S. commercial landscape, many involving credit-card numbers.

JPMorgan recently did an “oops” involving the personal information of 76 million client households. Other major hacks have been reported by retailers Neiman Marcus, Michaels, Supervalu and, just in time for last Christmas, Target.

My most recent online damage control — yeah, I’m a repeat victim — began Oct. 1 with a cheery email from Chase Fraud Alert carrying the subject line: “Your new card is on the way.” It went on to explain that “a security breach at The Home Depot” had placed our Visa Mileage Plus card “at risk.”

So I waited for the new plastic, dreading the chore ahead — especially because a month ago I accidentally wiped out the saved passwords in my Internet browser.

(Memo to self: Write down all user names and passwords on a piece of old-fashioned paper and keep that paper somewhere where you’ll remember where you put it.)

Ten days passed with no new credit card, just another email from Chase saying a suspicious charge of $0.01 had been posted to our card earlier that Friday at some place called “Silhouette Hair.”

Call me old-fashioned, but I still write checks and use U.S. mail . . . exactly for this reason!

I’ve been using the same barber for 30 years, but even I know you can’t buy much at a beauty salon for 1 cent. So I checked “no” in the box that asked if this was a legit charge and promptly called the Chase security hotline.

I was told our number was being shut down. The representative then checked to see if our new card had been lost in the mail. Turned out it was never sent. Oops. So he promised to overnight it via FedEx and told me that Visa would allow one final charge on the old card so I could reclaim my 2005 Honda minivan from Meineke, where it was getting new shocks.

Naturally, Visa rejected that Meineke charge. So I sheepishly paid with my Citibank debit card, drove home and waited for FedEx to deliver the new Visa on Saturday morning. That’s when the real fun began.

On half our vendor accounts I gave up trying to do it online and fought through their automated phone systems to reach human beings.

So what’s the moral?

For starters, vendors will keep urging us to “go paperless” so they can save on postage and pay themselves sooner rather than later. Consumers save on postage, too, while we rack up our precious airline miles and rewards. Sounds great. But until some young genius comes up with an app for easily switching card numbers, or for protecting those numbers in the first place, I’d go easy on auto-pay.

Sure it’s a pain writing checks and licking envelopes, but how many sunny Saturdays do you want to spend swearing at your computer?

John McCarron teaches and writes on urban affairs. He wrote this for the Chicago Tribune.