Handed over wrongfully.

I had an operation in July 2023. There was outstanding amount of R360 on my account. I paid it in November 2023 when I received the statement of account. I have since been handed over to debt collectors despite numerous calls and emails to confirm that it has been paid. I have sent through the POP on three occasions and still has not been rectified. And to get a hold of anyone who can assist, seems to be near impossible.