Handed over for payment made.

On a weekly basis, I receive FINAL NOTICE FOR LISTING for payment already done in September 2023. I did an EFT payment. The POP was sent to ER Consulting with my payment reference nr. Not long after that, I received a SMS that I have been handed over to Nu Debt for collection of outstanding funds. I was advised that if payment is not made, I will be blacklisted. I have on numerous occasions, sent emails, made telephonic contact to the collections department and HELPME at Nu Debt, but to no avail. This has been ongoing since December. Up until today, I am still harassed for payment and threatened to be blacklisted. The Debt Collector needs to ask ER Consulting to check their bank statement, as I cannot get into their bank account. I am now besides myself. I am not sure what more I can do and when will this harassment stop.