Receiving Final Notice altought there is a paid license

One month ago I recevied my annual TW invoice. Because I know how payments work on online websites, I checked how much would I pay if I would make the subscription from scratch (buy a new license from website, instead of paying the one received via mail). It resulted I would save 60 euros, so I paid the new invoice via website shop.

The license I bought as well as old license are both tied on same email address. When I started receiving mails from TW that if I won't pay the invoice they sent me automatically, my account will be banned. No problem! I said myself that if I notice TW Customer Support about this situation they will fix it in no matter of time.

But surprise! TW Customer Support told me that I have to also pay the invoice they sent me. I asked why should I pay twice the same license for year 2021 as long as there are both pointing to same email address. 

6 days passed and I don't have any answer from TW Customer Support, but I have FINAL NOTICES in my inbox. What can/should I do?

I repeat: I already have paid my license for year 2021.