Bad service!!

So they have been sending smses to me wrt NHLS account. I called, told them the R327-30 account was settled, on 5 January2018. They said to me the account was handed to them on the17 Jan. They ask for proof, they gave me a fax no. And an email. I sent proof...fax no never go through but atleast there was an email too. Few weeks pass, I get smses again and I call same thing happen, they give me a different fax no and another email adress, same result , fax doesn't go through but at least I also emailed. No response from them but smses still coming in and I call AGAIN. This time they say pay the account R614 or you will continue getting smses. For real!! Who says that??? I must pay them so they can stop harrassing me and avoid a bad credit record. I don't have any debts on my name except the bond account but I must worry about my record. My reference no: ********** ********** 67