I recently got an interesting letter in the mail about my Citigroup (NYSE: C) credit card:

The AutoPay feature on Account Online will not be available after July 22, 2011 (this applies to any automatic payments you currently have scheduled to be made after that date). After July 22, 2011 you must pay your bill each month using Citi Account Online, by mail, through your bank, if available, or using a bill payment service.

If this is confusing, here's the background. Most credit cards provide an auto-pay feature that automatically deducts a preset amount -- typically the entire statement balance -- from your bank account every month, on or before the day your payment is due.

This way, you don't have to remember to write a check, or risk facing big penalties when missing the due date by a day or two. Personally, I put everything I purchase on one credit card, and I relied on Citi's AutoPay to deduct my full account balance from my bank account every month. I didn't have to remember a single date, write a single check, or risk facing a single late payment penalty. Set it and forget it.

But now, Citi will end this convenience. Why? My gut tells me that by ending AutoPay, Citi ups the odds that customers will forget to make a payment, and thus incur large late penalties. Just one late payment can sometimes trigger higher interest rates and wipe out accrued rewards like airline miles or cash refunds. Citi, it seems, may be taking a step toward the Stone Age by deep-sixing convenient AutoPay technology, in a bid to suck higher fees out of its customers.

But let's not jump to conclusions. Maybe there's a good explanation. I called Citi to find out. Here's how our discussion went:

Me: I'm curious why AutoPay was removed.

Citi: Unfortunately, we had to make some changes to your MasterCard.

Me: Right. I'm just wondering why those changes were made. It seems like a very simple service that customers find beneficial. Can you give me any information as to why AutoPay was ended?

Citi: Unfortunately, we had to make some changes to your MasterCard.

Me: Is that all you can tell me about this issue?                      

Citi: Yes. Is there anything else I can help you with?

So much for the benefit of the doubt. If anyone can provide a good reason why Citi ended AutoPay, share it in the comment section below. In the meantime, here's a reminder to Citi about how low switching costs are in the consumer banking world: I've already applied for, and received, a new American Express (NYSE: AXP) card, complete with AutoPay. Step on your customers, and they vote with their feet. Ah, capitalism.

Fool contributor Morgan Housel doesn't own shares in any of the companies mentioned in this article. Follow him on Twitter @TMFHousel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.