Unfair account handover

I went to the ER at casternhof in February 28 2025. I was called and sent my account of which was paid. I got messages threatening me of handing over my account I know nothing about and was never sent to me or medical aid. The number showing is no longer in use and you get messages threatening you of handing you over. I am not sure why the invoice was not submitted and why they never said anything to me about the amount because the one they told me about was paid. I really need clarity on what is happening . They are really not treating client right and quick to handover