30$ data charge removal

I have a plan that that gives me option to remove extra add on of data which is 30$ per month. We have been trying to remove it online which it looks like you can but then when I delete it it says that its no longer available but still charges for it. Online wont do what it says you can and no way to contact T-mobile except to call which I prefer not to have to talk to someone that will try to sell me something. Any help on how to remove this 30$ charge which is a add on which should be able to be dropped.