Sam's Club review: Sam scam

I was an added member on a primary member's account. He did not renew his membership and did not have auto renewal so his account was closed. Sam's decided to charge ME for a renewal! I had to dispute the charge at my bank and they refunded the $50 back to my account. A few days ago, I saw another charge of $50 on my bank account regarding Sam's Club. When I inquired about it with Chase, I was told that Sam's provided them with documents that showed their charge was valid., so Chase made me pay it back. I'm now waiting for these so-called documents to arrive in mail. How could it be valid. One CSR that I talked to at Sam's told me that if the primary member didn't renew, they will charge the second person on the account for renewal. What kind of back yard scam is that?