Being charged a bill of R7800 for data!

A monthly bill from R115 for a data and ****le package ended up to R7800 for the first week in March. My history also doesn't show anything above R115 per month. I only use this in emergency purposes and remove it immediately when my cap runs out. Now I am getting calls from Vodacom for payment. Please explain how this occurred and why was I not notified when my bundle had been reached (if I was then the SMS came in late) because I would never make use of out of bundle to get a R7800 bill.<br> I will not pay this. Let alone I cannot afford to pay this! I do not have the money for this bill especially from R115 to a R7800 bill?<br> I have disputed this and do not have enough funds in my account and f this comes off my account I will take this up legally.