T - Mobile bad customer service, Internet

I got a one cell phone line and cell phone with t-mobile and for signing up with them they said they would credit my account and should appear on my bill within a week. so after that week had passed and i didnt see no credit on there, i went back to the same store asked where it was. They said we are going put it on there dont worry just wait. well i never did see on there even after double and triple checking. About some later my phone broke and i went to store and the manager talked to  headquaters and headquaters said they if  i called them they could replace my old phone with a new one as long as we send the old one in. I went home and called the t-mobile headquaters. They kept giving me the runaround saying we cant give u new phone without telling me why. I talked to bunch of different people and they all said the same thing. Even when they told store mananger that they could replace my phone. so yeah it has very bad custmer service.