Getting over charged by T-Mobile... and not getting any help!

I just found out today that since May of 2021 I've been charged $2.00 a month for a service on a device that I didn't have.  And because I'm legally blind and cat see all the details of my bill it didn't matter to them.  I get my bill online and the most they offered was to send them out as a printed copy as if I can read that.  They said it's my responsibility to find the errors in my bill.  How is this right or ethical I'm a senior widow living on a fixed income  I was just priced out of my apartment. And the most they offered me was a 3 month refund , I cried until they gave me 6 months.  But they took almost $800 from me.  I would like to know if there is a class action lawsuit for this kind of thing happening.  If not there should be.  I know that just as soon as I've paid off my device I'm leaving T-Mobile unless they pay me back.  This is wrong.