Enourmous account

I've had a data sim contract for more than two years now. Well actually a few of us at work has a sim with 2GB data on. Just received an account of R7800 for October?!? Phoned them just now, they cannot assist, only told me it is currently standing on R15800!!!! That there is no soft lock on any of these data sims! And that it is our fault! No sms warning, call, email, nothing! How big can an account get before the would do anything. Guess they just like it when an account ussually at R395 per month blows to a whopping R15k! This is unacceptable and should be *******!