Impossible Billing - *****

I have received numerous accounts for my data contracts with Vodacom. To the total or R11 0000!!! - And half of this was billed whilst I was out of the country... with my sim cards here in SA and off! How is that possible? <br> <br> No response to emails and never pick up the phone. <br> <br> I believe many people have had similar problems with data billing :( Lovely **** going on here I think! Fat cats sitting back using our data and charging us for it....grrr!!<br> <br> Who am I supposed to talk to to sort this out?