The CN22 code R25,85 charge is a Post Office Assessment Fee and not a SARS Customs charge.
As per the Post Office website https://www.postoffice.co.za/contactus/questions/postalrates.pdf on page 18:
Customs clearance (Handling fee):A customs clearance fee of R50,10 is charged on all incoming parcels and R25,85 on all other postal items. This fee is charged by the Post Office to cover costs incurred in clearing the parcel/postal item on behalf of the addressee.This fee is levied over and above any customs duties, VAT, etc charged by SARS or any other entities and is levied even if no other charges are due.
As the Post Office may change their rates and fees from time to time, please check their website on a regular basis for the most recent and correct amounts: https://www.postoffice.co.za/contactus/questions/postalrates.pdf.