Payment arrangement (denied) to loyal customer since 2004

I'm very disappointed in AT&T, I tried making a payment arrangement and I wasn't allowed to cause I broke an arrangement by 2 days. Are you Serious??? I have been a customer since 2004, and your really going to tell me that. It's very rare for customers to be with a company that long, and when you do you expect alot better customer service then the one I received. That is just one issue there are several more, now I'm definitely thinking about finding me another cell phone carrier. I'm just tired of you guys treating long time customers like crap. My question is why are you taking a chance on losing a loyal customer because of a so called broken payment arrangement by 2 days?