Is it normal customer pay the difference after a business incorrectly charges them?
I recently have been paying for a service for about a year and have just been okay with it, but there aren't many other options in the area. Anyway, their price initially was about $20 cheaper per month than it is now. I guess they increased their prices six months ago, but never notified me in any way, shape, or form and didn't even notice that I had still been paying the old price until today. They did say that it was their error, but asked me to pay the difference, and I had no problem with it. However, when I brought up with my close friends how weird it was that it took six months for them to realize the error and that they must've not been looking at the amount on my checks before they deposited them, they told me that them expecting me to pay the difference was incredibly poor business practice.
I understand that they need the money for their service, but are my friends right? I'm not planning to do anything about it now that I've already paid it, but I'd like to know in the future.