NuDebt - TV license

Every year for the last 30 years I paid my TV License. 2024 the SABC did not send me a SMS reminder as usual, so I forgot about it and paid it late. BUT I DID PAY MY TV LISENCE, with other words, my TV License is up 2 date at the SABC. Now this dudes as NuDebt is calling me every second day regarding an outstanding account. I must pay the a further R106 because I paid late. I refused to pay them interest, because they can not prove to me that SABC send me a reminder, or that they are a financial service provider (in SA only financial service providers are allowed to charge interest, except if there are a agreement in place), or show me the contract where it state that they are authorized to charge me interest. Today I got a SMS that I did not pay as promised, but now it is R150 because of penalties. I state it clear again, my TV license is paid in full to the SABC. Please help me to get rid of this people.