Excessive data billing

I logged a call on 11/05/2015 Ref 682568. My previous request just disappeared. I have a Laptop & data contract limited to 500MB. I don't use the sim for data at all as I have Wi-Fi at home. In March I was chanrged for 900+MB data used and in April 2.9GB data used @ R2080. This is a rate op R890+ per gig (considering that the 500MB is included). <br> <br> I talked to Maggy Taunyane on 07/05/2015 as I wanted the Detail Billing, URL's used as well as IP of the device used. She sent me the March detailed billing via email and I emailed her back to ask for April's detail billing. Still no reply and still no word from Autopage on my log of 11/05/2015. <br> <br> How is it possible that a data account limited to 500MB can build up an account for 2.9GB? Specially when the account is NEVER used for the data. The account was purely for the laptop and nothing else. And R890+ per gig is ****************. I monthly buy 3GB data for R249 for my Vodafone tablet. <br> <br> I need answers because come end of the month, this debit order will not be paid from my bank account.