Is there a Vodacom contract with NO out of bundle data?

Hi

I am looking for a cellphone contract, with data, but NO out of bundle data.

I want to specify a 200MB bundle, then when the data runs out, I get capped until the end of the month. If I want more data, I log into to website and buy a once-off bundle.

However, I want a contract with this. Calls are billed normally and the data I buy is added to the bill and I pay at the end of the month.

I heard Cell C has this, so I thought I would give Vodacom a chance firts, before I move my account.