Requesting Magenta Max 20% off insider code

I moved to Tmobile and the store guy set up my account with 4 lines with Magenta Max. He gave me 20% off with an insider code last week but i am still waiting for it to be reflected in my bill which is already out and due on 15days. Anybody knows why is it taking this long ?? when he checked the status it shows submission received. He says it's a matter of days but it has been already a week since i opened this account. Gracias