In-Store Representative Lied to Make Us Sign Up, T-Mobile Support Won't Make It Right

We were made to sign-up under false pretenses that we would be receiving a 20% monthly discount ($34) for the Magenta MAX plan from an in-store representative. He claimed it was for friends and family, and that he'd use it for us to entice us to sign up.

2 months and multiple trips to the store later, the discount keeps disappearing from our account. The store manager (Ryan) was helpful and provided us with bill credits and a new code when he didn't know what the problem was. Eventually I called T-Mobile Support (611), and they've informed us that we were never eligible for the code, and that it's too bad and we have to deal with it.

I'm furious that T-Mobile could just lie to our faces and coax us into signing up with them under false promises (which we have paper trail documents from the in-store employee), only to have them yank it out secretely and told to "deal with it". If this issue isn't resolved, we are likely to cancel our plan and never recommend to any person with a conscience. This cannot be legal, I don't believe it so.