Fustrated and Dissapointed

I have been unemplyed last year so I made payment.arrangements with Nedbank.When I started working again I made arrangements to pay for the arrears. This was a PTP and since I hareimployed they have been double debiting my account and when I call for the refund they say the PTP is not sufficient or exp. I have to call and waste airtime to get my money back each taken the full installment and PTP amount. What is the point of making arrangements when the service provider cannot keep to their word. I have told them I am contactable after 4 but no they still call me before that so they have an excuse to take my money. This is not acceptable and I deserve proper service with integrity. And competancy. I have asked for a senior person to call me but no call to this date. Thank you as you have taken another R3405 without my authority