Unable to get help with upgraded service very confused and frustrated

I discovered that service I had been told was "unlimited" years ago never was and that I had been charged dpuble each month for going over (who pays $200 for 400mg)??? So chatted  in for many hours last week to determine what had happened and to upgrade plans to better speed and unlimited. Was told it would take up to 24 hours... a week later still do not have the upgrade so about to hit the max about get double charged again for going over. I even had received a text and successfully signed a contract last week. Tried to call and chat in today about it since there is "an outage in my area" I am not allowed to speak with anyone. Finally got an agent but only allowed to talk to new customers or something and agent made told me it was my problem my new service didn't start because I didn't receive an email confirming the upgrade.  Was told we didn't need a new modem but when I try to place the order myself not only is it a higher price but also says that I can't use my current modem ( that is fine with me but contrary to what agent said) last week. Agent gave me a refence code for the chat  187854314494985438 but it is useless.