Dissatisfied with Nu Debt service

Today made a call to Nu Debt Management and spoke to Thapelo call reference *** which he refused to give to me as he refused to call his supervisor to correspond his story that I can't make a payment arrangement on my SARS overdue amount, he said he is in charge and will send me an SMS to settle even when I told him I have supporting documents that show I'm unemployed with a certificate of service rendered to me during a section 189A. I'm displeased with the customer service as I was denied a supervisor, a payment / d/o arrangement and promised payment details to be sent via SMS to settle but are not sent as well. So I'm asking for proper assistance and customer care please.