I had a similar issue, customer service doesn't have a clue ever about anything. So I asked to talk to someone in the Retention Department. I got a bill credit for a free month's service ($130 roughly) AND got the upgrade date on my 2nd line reset to be eligible now instead of in 12 months.
I got this person on the line, and said I have friends who were offered the $70 Loyalty credit applied to their account for renewing their contract. The rep looked it over for a bit, then let me know that it is only for customers with 11 months or less remaining on their contract. I was at 12 months, so she said she couldn't do it now but could in another month.
I said I would like to talk to someone about having it credited now instead of waiting, because I wanted to upgrade to the Evo 3D and didn't want to wait a month to do this (note they apparently aren't aware that I already upgraded my device on Friday 6/24).
She came back and said if I'm looking at upgrading, then she would reset my upgrade date on my 2nd line (which is currently 12 months out and is my brother's line, I already upgraded my line on Friday 6/24) to be eligible now, and once I buy a new device I can call customer service back and they will give me a credit for 1 month service (I'm on a family plan, so that is about $130).
Key lesson I think is Customer Service reps rarely know what they're talking about, and most often don't have the ability to do anything. So talk to someone in Retention. Don't be an a-hole, but be persistent.
