need help with contacting TMobile corporate office

I have several numbers I found online that I am going to try. I am also going to be contacting attorneys in regards to filing a lawsuit with the company. I've been with them for 2 weeks-switched from Sprint (who I was with for 10 years) because they promised me I'd be grandfathered in under my Sprint monthly amount only to be billed a much higher amount and basically told yeah we promised you that but it's not going to happen. And oh yeah, we also promised you a free phone for switching but you're going to pay for that too. It's been a NIGHTMARE of hours spent and being constantly lied to and then basically told I'm screwed.