MISLEADING Pricing

I went to my local postnet yesterday to enquire about the R99 postnet to postnet deal. I SPECIFICALLY asked what size the box needs to be in order for it be still qualify for the R99 deal and the guy at the counter says he couldnt give me exact measurements as it could be long and short or round or whatever and fir or not fit into the deal. SO WITH LITTLE TO NO INFORMATION I LEFT. From the adverti*****ts I remember if the package was under 5KG then it costs R99 so I packed a box and it was 4,9kg. This morning I take it to that same postnet and they measure the box and instead of it costing me R99 they were going to charge me R159.00 then I ask AGAIN what size the box had to be and a DIFFERENT guy gives me the box that would fit into the R99 deal. Then another cashier tries to argue with me and tell me that SHE TOLD ME - I never even SPOKE to her!! ALL the posters EXCEPT ONE ALL SAY r99 for a box under 5kg and say NOTHING ABOUT VOLUMETRIC WEIGHT. The ONE POSTER says something about VOLUMETRIC WEIGHT, and the print on that information IS SO SMALL and the poster is hidden behind a machine. HONESTLY?? BE MORE DECEIVING! This is the second time I have had issues with postnet here by me, I will never ever again use postnet for ANYTHING. I would rather pay Aramex double. Im so horribly disappointed.