I had the same experience
The same thing just happened to me. I applied and got the United Card with the understanding that I would get a $250 statement credit. I used the card for a United Flight and some other purchases. A couple of statements went by, but the credit never appeared. I just called Chase cards today, and they said they knew nothing about any statement credit, and told me to call United. I called United and they didn't see any record of the $250 credit either, but put me in touch with a liaison between United and Chase. He admitted that a lot of people were in the same situation and were complaining about it. He apologized but said "there was nothing he could do, because I signed up for a different offer." So I am guessing they had some kind of deceptive layout to their application process, so that as I was going along with my application, I was no longer applying for the offer I thought I was. I consider it a fraud and a scam. My significant other applied for the card right after me, and she was able to get the credit. I guess she was more careful than I was and didn't fall for their trick. I am still not sure how it happened. All I know is, I thought I was applying for one card (with $250 credit), and I ended up with something else. I am upset but don't know what to do about it. If anybody has any ideas of how to get some satisfaction and justice concerning this deal, please let me know.