Netflix complaint: Double payment

Hi
Last year my husband got a free subscription for a year with his phone deal so we didn’t have to pay for Netflix. When it ended I tried to sign up for a free month but it wouldn’t let me and when I called up I was told it recognises the IP address and we already had the free month under Stevens email. At this point I subscribed with my email and I pay a monthly fee directly from my bank.
However when my daughter accidentally tried to sign in on her laptop with the previous account details (my husbands email address) Netflix was quite happy to take a second payment (from the same IP address) ! And it only didn’t go thru because my husband blocked it through the credit card company!
I think it is appalling that Netflix chooses when to recognise IP addresses.! When it came to “giving away” a free month they couldn’t but when it came to taking a second payment for the same service- that’s okay!!!
I am shocked and dismayed! We shouldn’t have had to even cancel any accidental double payments. We hope this won’t affect our credit rating!