Never received promotional prepaid cards for mobile switch

Purchased phones in September after paying off att bill and unlocking phones.  Purchased upgraded phones and switched service to xfinity. Promised prepaid cards in amount of phone payoff which was 415 each for a total of 830. All documentation uploaded and old phones returned. Receives a ln email on 9/18 that phones were expected and the 830 would be coming. We have received nothing as of today 12/30. This was a driving reason for switching and this seems to have been a scam.  I am needing answers and the 830 dollars!