Sam's Club review: Requested new membership only - associate signed me up for a mastercard

I went into the Cape Girardeau, Mo Sam's Club on 1/30/22 around 12:00pm with a coupon for a new membership at the basic level. The coupon came through the mail and was only for new members. The coupon stated 45$ New membership would give you a 20$ E-Gift Certificate. The associate went through out the set up process took my picture and had me enter my email, my ssn and my income. This is the first time I've signed up for a membership under my name so I'm not familiar with the process. She asked me what level of membership I wanted and I said basic. After she printed my temporary card she told me my new one would arrive in the mail in 7-10 days. We continued to go through our shopping list and then went to the check out lane. When I was in the check out lane the cashier asked me if I would like to pay with my Sam's credit card and I told her that I don't have a Sam's credit Card. She said "Yes you do it shows right here" I said I absolutely do not have a credit card with SAM's I only signed up for a basic membership today. It turns out the lady at the help desk signed me up for a Mastercard with a 5,000$ limit without even asking me if I would like a credit card or going over the details of the card. The cashier apologized and instructed me to call the credit card company to cancel. I wouldn't have even known I had a Credit card if we hadn't went through the cashier check out. My fiancée was with me when I sign up and he was appalled. She said absolutely nothing about a credit card. We went back to the help desk and the lady assisted me with cancelling the card. She explained that I should be receiving a letter in regards to the cancelation within 7-10 business days. I checked my credit report and it is already showing an inquiry and -11 points off my credit score. This was completely unethical and I'm not sure how easily this will all be resolved. I'm hoping they will be able to remove the inquiry from my credit report. I really want to make sure this doesn't happen to another unsuspecting shopper. They need to be clear of exactly what they are doing. At least give the shipper the option to say "No, I decline the Credit Card"