Lied to on recorded line and no one will fix the issue

I had phone calls with 2 Service agents and my fiancé. We were told blatantly a price for everything included. we asked multiple times and event he customer service reps asked each other about it multiple times to confirm. They said if its not right reach out and everything is recorded and it will be taken care of. Great so my bill says a very different amount. I reach out and the guy doesn't answer the questions and cant tell me what charges are for. I get a supervisor and h e tells me basically he cant do anything besides change my plan to a cheaper plan and that's it. Is there a way to get this actually resolved or is this just typical T-Mobile and i should cancel everything and switch carriers? I'm at a loss how i can be promised over and over 1 thing and told not to worry just reach out if its wrong and its all recorded and they will take care of it and then when i do nothing happens besides to bad.