I would be too but hey I'm always disappointed by Vodacom.
You should probably upgrade to a LTE-A device if you want to see faster speeds. Phones that supports only 1 LTE band is almost always going to suffer from slow speeds. Force it to 3G only might get better. With the massive increase in cheap LTE smartphones band 3 on most networks are congested as hell and you will find that 3G is faster than Band 3 on 4G.
Charge your phone dude lol. Seriously though Vodacom claim their prices are because of their infrastructure. Which is not really the case. With regards speeds across all networks it's like a lucky packet.