Gap review: unethical behavior and misrepresentation

I was at the Gap store in Garden City on Jan 15th. When I was checking out, the cashier was interrupted by someone who seemed to be a manager. The woman advised me that I was eligible for a upgrade since I was a long standing member and spend a lot of money. I told her that was fine and asked if I would be getting another Gap card. She said yes. She never advised me that I was opening up a Visa credit card. I went on line to pay my bill and didn't see the items showing yet. When I looked again on line, I noticed a new credit card with the purchases I made. I called Gap immediately to close the misleading account and paid off my balance. Now my credit score went down 30 points with TransUnion. I don't recall the woman's name however I have my receipt and the Cashier# is 3143803 and the transaction number is 7496 Cashier no 004 store # 02550 Sales 8340. I will indeed go back to the store to obtain the woman's name but so furious that I wanted to make this complaint immediately.