Debit order of R120 000!

<p>My mother's MTN account for Oct 16 was a whopping R120 000 (give or take). The first she heard of it was when the debit order went through... she has subsequently had this reversed, but had the same issue last night.... </p> <p> </p> <p>Her account (for 3 contracts) is normally in the region of R2 000. She has lodged a query, but MTN simply says she has to pay up... </p> <p> </p> <p>She has a credit limit of R3 240... so I would like to know how this could happen. My own line was suspended during the week because I exceeded my limit of around R3 000. Why didn't this process kick in on her contracts? </p>