I am SO upset!!!

I recently moved and transferred service for at&T. Last time we transferred service, there was no fee. AND now I am being charged a $149 fee that I was NEVER made aware./ This is theft and I used my entire lunch hour to try and rectify it. Even though AT&T could NOT provide me with one inkling of when I was ever informed of this charge, they still will not remove it. I am livid. I have been a great paying customer for almost 10 years and they not only want to steal from me but be stubborn and now reverse the charges. It isn't the amount of the charge so much, it is the principle. Now, we will have to seek legal action....over a minuscule $149 and change providers. Shame on them! Who in their right mind these days thinks it is okay to steal....from customers? hard working honest individuals? anyone for that matter. Very disheartening!