real life beat

As some of you may have noticed, my internet disconnected yesterday. I decide to have an early night and today I tried reconnecting, it still wasn't working.
I decide to phone my ISP support hotline and they tell me that my internet has been locked, because my bill is already too high (my rate is 24€ a month with 15gb limit).
I ask them how high and they say 500€ (roughly 700$). At this point I am in a wtf mood, but I am not even really pissed, because it's such a ridiculous statement on their behalf.
She says they'll only unlock it if I pay the 500€ cash! I try to figure out why my bill could possibly be so high and she tells me that she can not tell me that yet, she has to wait for the details on the bill.
I've just been to the store to talk to somebody in person (whilst on the phone to support I asked for somebody in charge, but she said nobody could review this at this time).
The guy at the store seemed reasonable, agreeing that it's virtually impossible for me to have such a high bill.
I really have no idea how this could have happend and it is really annoying. I'll update when I have news on this.
ffs...