Money-grabbing incompetance

This courier service is grossly incompetent and unprofessional. I sent a parcel that weighs exactly 1kg from Pretoria to Bloem and got a mail that I am being fined R100+ because my parcel "weighs 4kg". Upon contacting them they let me know that "The couriers charge the greater between the actual mass and the volumetric mass". This was not disclosed beforehand. I was not asked what the volumetric mass of the parcel is. I was not told that the greater of anything compared to anything would be used to charge me. This abysmal technicality is used to not only infuriate customers but charge them well over any logical fee. On the photo they sent me as "proof" that I should be fined, taken by the machine of my package crossing the conveyor belt, it is clear that the package weighed 1.25 kg. I paid for a 2kg courier bag. Charging me for a 4kg parcel and handing me a fine before I can use their service again is an unprofessional, money-grabbing far stretch.