Unexplained Data Usage Bill

I have been a Vodacom customer going on 20 years (with the SAME number). I received my latest statement (01/06 - 30/06/2015) to find an extremely high amount for data usage. Usually my bill is approx R700.00 per month and now it has jumped up to +R1700.00. I have received a Vodacom URL REQUEST DISCLAIMER form to sign in order to receive the breakdown of data usage BUT on the form in the 1st paragraph it states that \I have unexplained data usage on this number"and then in the 2nd paragraph it states \""I am the entitled to this information as the usage was generated by myself\"". How can I admit to something that I have no proof of doing????? and why should I have to sign this in order to receive the necessary information required as I am being billed for this. There should be a 'cut-off' amount with regards to data bundles. Customers buy certain packages to suit their budget and do not like surprises at the end of the month. There appears to be NO feature that can allow a consumer to control and limit their spend. How can I receive the necessary information for the data used in the month of June 2015?"""