Rude consultants and lack of clarity

I have an account that was paid up months ago, but for some reason, received smses and calls from this company. They claimed I owed an amount that was incorrect, and cited that it was a different account - which is not correct. I contacted the actual medical company for the amount owed and they stated that on their end, the account was I have been sent from pillar to post for months. I have contacted them via email, whatsapp and telephonetically. No information is put on the system and every time someone calls me from the call centre, I have to explain from the very beginning. I am beyond frustrated at this point because I wont pay the same account twice. But Im met with attitude from rude consultants each and every time. And they dont call back when I say I am available to have a proper conversation regarding the matter. Including the last rude consultant I spoke to last week who insinuated I was the problem. I have all of the records regarding communication. Nothing has been ignored or avoided. And this is simply not on. No one communicates with each other and no one seems to know what is actually going on regarding my account. And I've asked countless times.