Appalling SA Post Office Registered Letter delivery

I am currently trying to take previous tenants to small claims court, which requires you to send a registered letter to them after which they have 14 days to settle or after 19 days a case date can be set if they do not collect registered letter... I sent the registered letter on the 24th of December 2020 and it is still in transit sitting in their hub WITSPOS arriving on the 6th January, 2021. Today's date 19th January 2021, which means I still have to wait until registered letter slip is delivered to their address and wait another 19 days if they do not collect to get a court date and by then we might be in lockdown again! Service is shocking and Small claims court need to start accepting other forms of delivery of letter of demand!