credit on my bill 100$

I had talked to customer service for three weeks in a row 4 hours a day every other day whenever I first signed up with you guys and they assured me that I would be getting a 100$ credit card sent to me from T-Mobile for my bill, but I still have yet received it nor did it ever get credited to my account. I really don’t want to spend another 4 hours on the phone today to solve this.