Billing issues every month and promotion at time of signup not honored

I am having a slightly different issue, but just like you TMobile keeps giving me the run around and I have to call them every month to adjust our bill. Each Customer Service Rep says the same thing " we are so sorry to hear that, I am so sorry I am just trying to help, I am so sorry your trust is broken, I will try to fix it for you" and then the next bill comes and something is wrong. I almost want to file a consumer complaint with the State or BBB at this point.