Important Documents Not Delivered

A month ago on 17 April I posted a large envelope from Dublin, Ireland to Durban via registered post with tracking number RL 543 693 501 IE. The envelope contains very important transfer documents for the sale of my property and the attorneys said that they have not yet received the envelope. I have already emailed three different customer services email addresses including JIMC asking for the local tracking number but they have not rep**** so don't ask me to email them. The envelope only contains three pieces of A4 paper so the late delivery is not due to it being held in customs. It has been a month and the attorneys urgently need the envelope and I need the local tracking number.