Excessive R8448.09 bill due excessive data usage

I upgraded on the 20.01.2016 quotation reference ***5. My upgrade from SMART L to RED Advantage and will only take place on the 31.01.2016. The handset I have is an I phone 6S<br> <br> On the 28.01.2016 I received an SMS Alert : Unusually high usage has been detected on your cellular number exceeding R6991.04.<br> <br> When I logged on to the Vodacom app I was stressed out my bill so far is R8448.09. I called the customer care line but was left without no detailed bill or explanation. <br> <br> Please help how is it possible to use so much data, I am a loyal customer and my bill has never been so high. I cannot afford to pay R10 000 for a one week's data usage.