Ever saw a TOP UP account being billed R2500??????

Since when does Vodacom send R2500 bills for Top Up 150 Accounts??? I'm a 60year old lady that has a extremely tight budget every single month. My debit order went through on the first of this month for R2500 for the first time in over 2 years on the exact same contract. I went to the nearest Vodacom branch to find out what the problem was and I was told that the system states I have an \Open Contract". On a TOP UP ACCOUNT??? I asked them to get my original contract that I signed which confirmed that I didn't asked for an open contract but merely a top up account (which should work basically as a prepaid account). I went to the bank to write back the debit order and 2 days later my account was soft locked. After 3 visits to the branch"