Visa Gift Card Promotion - Xfinity Mobile

I signed up for Xfinity Mobile on March 17th of this year.  When I signed up, I was given the option to bring my own phone or receive a $100 gift card per line.  I transferred 2 lines and I chose the gift cards and was told I would receive them after 90 days of service.  It is now July and I have yet to receive them.

I called to ask and the first representative explained that they were emailed to me in June and I must have deleted the email.  They told me to call the Visa cards department and but they had no record of the gift card being issued.  

I called back and the second representative informed me that I actually was not eligible to receive the gift cards because the promotion ended on March 6th.  I have email proof from Xfinity stating that the promotion was valid through March 21st.  The rep said they would need to raise a case with the back office to investigate and and I would hear from somebody in 2 business day.  Nobody reached out to me after several business days so I called back and was told there was no such case.  The story keeps changing and every rep just wants to pass me to the next so they do not have to answer my questions.

Every person I talk to now transfers me, and it seems nobody cares that I have proof of the promotion.  I do not know where to turn.  Every time I ask to talk to a supervisor "they are unavailable".   I would like to talk to somebody that can help with this request and provide me actual next steps to receive my gift cards.