Chase United Card

Four months ago, I received application approval for the Chase United MileagePlus Explorer Visa Signature Card, with a minimum credit line of $5,000.  At the time, the sign-up bonus was:  30,000 MileagePlus miles after the first purchase on the account.  My mother informed me that I had received an offer that was 50,000 MileagePlus miles after spending $1,000 within the first three months.  I called the phone number on the back of my Visa card, and the female representative reassured me that she would upgrade my promotion to the one I had received in the mail!.