REFUND NEEDED URGENTLY!!!!!

I have an account with Vodacom (acc no: ***4-4) for my apple ipad which is a to up account which worked very well and my monthly bill was within the stipulated limits (less than R500 a month). In November I received a bill of R20 000 which was really odd as my data utilization is on emails, research articles on google which I have been doing anyway, I also never received an SMS that I am over my data bundle limit however the account was only blocked at R20 000. The question I asked was, shouldn't the blocking happen as soon as I hit my contracted limit? Why wait until R20 000? And why not communicating to the Customer? I NEED A REFUND OF THE R25 000 URGENTLY.