Final Notice Received - Despite Amount Being Paid

Received a final notice to settle my account from Torga - Moffet on Main Port Elizabeth.<br> <br> Their letter states I have apparently been notified repeatedly. in fact I received one SMS and I then made an EFT Payment for the outstanding amount on the same day.<br> <br> Two months later I receive this final notice dated 20 May 2015.<br> I receive this notice on 27 May 2015 - stating I have to settle the amount before 30 May 2015. (Torga inform me of their intention to take legal action against me) <br> <br> Today when I phone the practice to find out what was going on