Honestly, you were most def. in the right to object to paying. I used to have SO many issues with my phone company. I don't know how it works in your circumstance because you are going through a larger company, but if you complain enough (with a professional but stern manner) and speak to supervisors or threaten to cancel your plan with them entirely, they usually throw you some free perks and comp you account for whatever bogus fee they're trying to charge you for.
Telephone companies, cable companies, etc they all these departments that are trained to basically bend over backward, and give you anything they possibly can by rearranging things in order to KEEP your business. So don't accept their mistake at all. You have every right to fight that and you should def. so. You might even go to your boss yourself and tell him/her the situation before the phone company does so. Also, most of these phone calls are recorded for quality assurance, so if you/your boss wants to fight it, it shouldn't be hard to tell the supervisor that you'll have the recording brought up in small claims court and fight the extra fee because one of their representatives misinformed you when it is his JOB to provide you with accurate information regarding your account.
It also kind of sounds like the old bait and switch deal. A lot of companies like to scam you by saying you can get the upgrade like they did and then tell you they were wrong and you need to pay. You can't return the phone because you've expired the return length in their policy etc etc. Don't pay it! This is THEIR problem, not yours.
On a side note, how do you like the 4S? I heard it was having some battery issues and that the voice thingy doesn't work well in Canada, so I just got the 4G, personally.
