was promised gift card to sign up and still nothing

I was promised a $400 gift card for switching to comcast by a comcast rep.  It has been a year since signing up and I still have not received it. That was a big influence in my decision to switch. Every time I call to question I am told to keep waiting another month, another month, another month...etc. If this is how it will continue to be I will have to consider switching providers.