Can you expand on the 'negotiating' part?
Sure.
It's very useful to use courtesy and to state the obvious. If we think about it for a moment, these customer reps have a difficult job.
Many people that call in are angry and difficult. So when the rep hears a pleasant voice from someone treating them with respect, they _want_ to work with you. Upon answering your call they don't know anything about you.
So I kindly make my request, then let them know I'm a loyal customer. I pay my bills on time, and I have a high lifetime value to them. That's why I choose not to threaten to move to another carrier. I make a point of complimenting them on the good service AT&T has always given me (which is true).
I've never had any problems with dropped calls or any technical issues in the twelve years I've been with them. It changes the entire tone of the conversation to positive and happy. I'm simply asking to be rewarded as a good customer by giving me an upgrade price & waiving the fee & time requirement.
The benefit to them is they sell one more unit, which is how they are judged by the phone manufacturer (units sold). The benefit for me is a new phone at the lowest price whenever I want, directly from a corporate AT&T store.
Finally it's important to remember the first person you talk to is not a decision maker. They don't have the power to fill my request. So by thanking them for their time & asking for a supervisor, you end up getting the person that can authorize the request.
By the time I'm done they are happy and genuinely thanking me for being a good customer. It's quiet easy when you are nice to them. You get the same courtesy in return. It's a win/win deal.
That's what works for me & enables me to get a new phone each year before I'm eligible.