Vodacom taking phone off network despite payments being made

My partner made a payment arrangement with Vodacom due to not being able to work until level 3 of the lockdown, she has continued paying this arrangement (despite not having an income) and then she sees that Vodacom tried to debit the full outstanding balance (which is roughly 3 of her arranged installments) without even discussing it with her and, when it bounces, they send her a sms to say that they are moving her to a "prepaid service" due to "non payment" and her phone is summarily cut off completely and she cannot even receive calls with no "prepaid service" in sight. 3 weeks and multiple visits to her local Vodacom store later and her phone is still 100% off the network and nobody seems able to help her resolve this. This is extremely dangerous (for a young female stylist who drives alone at night and makes house calls frequently) and completely unacceptable and unprofessional.