Vodacom call centre unable to assist with data usage item

I have a query about data usage for secure encrypted login. I don't know what this is. Google tells me it is what allows me secure access to websites and apps requiring additional security so I am guessing this would include email, banking apps and WhatsApp, for example. But why is the data usage showing up separately from those as an additional billing item?

I am asking the question here because the vodacom call center dont have a clue what it is.