Just so that I understand- you agreed to the $20 phone fee,and now you want to try and dispute a charge that you agreed to? During the dispute, will you mention that you agreed to the charge at the time?
I should say that I completely agree that charging a fee for something that can't be done online is totally bogus. But the charge is disclosed, and you agreed to it. Trying now to dispute the charge seems inappropriate especially as one would likely have to lie and say that the charge was not disclosed to have any reasonable chance of success.