Poor service

I send registered letters at Postnet at Arconpark Vereeniging on 22 October until today the letter is not in Pretoria They told me it will take 3 days My ex no RC 163 919 225 ZA The letter is important that is why I send it as a registered post I phone the call no and they told me 12 Nov that my letter is not in Pretoria Who can help me so that the letter can be delivered before Monday 15 Nov 2020 Help me to deliver the letter