I worked for a while as a CSR for AT&T wireless. The policy for billing adjustments is as follows: If a customer has had a rate plan change within three months of the dispute, and the new plan is drastically different from the old plan, they should issue credit.
Call them again, and ask them to read to you the notes made by the representative who consolidated your account. If the rep didn't note that they advised you of each and every little thing, you are in the clear. It's your word against theirs.
It is very easy to mis-click and remove features a customer previously had. Also, some reps get a little over zealous and try to help you out by adding features that really don't belong on your account. When the change is made, there appears to be no immediate problem. The problem happens when the automated system called "back fix" goes in and removes non qualifying features. That will also cause huge overages.
When you speak to the rep, you need to have your notes in front of you.
Spell it out, line by line like this:
"Up until X date I had X service plan with X features."
"On X date I consolidated my services and was advised that I was placed on X new plan with X new features."
"I was never advised that my unlimited night and weekend package was being removed."
Oh, and grantg24, those morons in customer service can do a whole lot more for you than the president can. The president and CEO (Nadir Mohamed) never takes inquiries from customers. His schedule simply doesn't allow for it.