Pathetic service

Good day, My Mom has been using her no since 1996, it started off as a contract and a few years back she went to prepaid since well she's a pensioner.

Lately they keep on blocking her no saying she owes them, last week they said she owes R56, an hour later they said it's paid, by whom we don't know.

This week it's R90, they blocked her no again and it's been 2 days now, where do they get this amounts from? Why now?