From the screenshot you really were assigned a 100.X.X.X IP address. Looks like someone at Vodacom made a typing error. As I mentioned earlier this is a reserved IP address and is not routable from the Internet.
Call Vodacom Customer Care or send a PM to VodacomData.
Very possible they are using it as an internal range. A what is my IP type lookup will quickly tell you if your traffic is being NATted.
From my recollection unrestricted apn used to give you a 41.192.x.x IP.
