Unprofessional & rude

I have paid my tv license, however i still got a call from Hahn collections informing me of outstanding debt. I have sent through proof of payment as well, however, I am still been harassed to pay my tv license. When I contacted Hahn collections i get told to ignore the messages. I could possibly be blacklisted if their system is not up to date. Unfortunately my conversation is on a whatsapp line so i have no clue who I'm chatting to. I was also told that I'm being unreasonable??!! really?? Very unprofessional service. Outstanding debt has been paid, update your system, inform the client that all is in order. I should not be receiving messages demanding for payment, when it has already been made.