Finance department threats

In June I short paid my account by R100 - my mistake, I acknowledge this. Then I received a call in the middle of July to inform me that if this is not rectified steps will be taken. I paid the full payment this month as well as the backlog from the previous month on Friday already. But still this morning I get threatening sms's telling my I did not pay as agreed and if I do not pay today further action will be taken. <br> Please make sure of your facts before threatening. This is ridiculous and absolutely unnecessary. I will be paying my account off and closing it as soon as possible as I do not deal well with threats.