Data Usage Bill of R5600!

<p>My monthly Vodacom bill is R289 which includes a 2GB data bundle... I have been paying this R289 for almost a year. I have just received a bill for R5600! The invoice merely states "Data Usage" with no further info or details. I contacted the Call Centre and spoke to a lady that was completely useless. I asked her how it was possible and she said she is not able to tell me... I asked her how this could even happen if I only have a bundle of 2GB wherafter the usage should be depleted and the account suspended but she could not give me an answer... I aked her to then cap it so that whatever happened does not happen again and after putting me on hold she cut the call! So now I owe Vodacom R5600 for "Data Usage"??? I don't even know what that means and the Call Centre is so useless that there is no point in even trying to sort this out!!!</p>