No invoice recieved but Pre Legal letter received

I am in absolute disgust in the way in which my apparent outstanding debt has been handled., I had previously received 2 invoices totaling R3489 (Refs Y*** & Y***) which I promptly paid in July. I am now suddenly in receipt of a 'Pre Legal letter' for R284,72. I would like to point out that I have never received an invoice for this and perhaps I am the one who should be seeking legal action. <br> <br> Had I received this invoice for R284 why would I have not paid in light of the fact that I had previously paid R3489?? <br> <br> Despite this, I have paid the R284 but I now require a copy of this invoice as well as an apology. <br> <br>