Poor service from MTN consultant

I phoned MTN on 13 March for an upgrade on my cell phone contract. The consultant who helped me was Nicolette Naidu. Everything was finalised and the service was good. On 22 March I phoned again to ask if it is possible to change the Handset I have chosen, since I am hearing impaired and the new hearing device I am getting required an i-phone. I did not know this on 13 March when I did the upgrade, and on 22 March the new hand set was not delivered, hence my request. I was told by Colette that it was possible, and that is when my problems started. Since then she doesn't respond to my email inquiries regularly and when she responds she tells me that MTN is still waiting for the handset to be returned. I then contacted the delivery company directly and according to them the handset was returned on 22 March. I informed Nicolette accordingly via email and she responded to the email. I emailed her again on 5 April and 16 April, to which I received no reply. Only when I complained on Hellopeter did she phone me saying that there is no need for me to complain on Hellopeter as she is aware of my query and she has made a note of it to follow up. Yesterday I emailed her again asking for an update. She responded with a waybill number, saying I can contact DSV directly if I want to follow up. Since I have already phoned them and they confirmed the handset was sent back, and Colette explained to me that it now takes time for MTN to get the handset back into their system, I don't understand Colette's response and I don't know what more I can find out from the delivery company. To me it feels as if Colette does not want to help me. Because of the delay I couldn't get the hearing aid requiring the i-phone to operate, and had to settle for something else. I emailed Colette back yesterday at 12:33 to tell her that I don't understand her email. She didn't respond. I emailed her back again at 12:39 asking for the contact details of her supervisor, because based on her previous lack of responses I expected that weeks will go by without her responding to my email. Can someone at MTN please look into this matter, and get another consultant to assist me? As a hearing impaired person I feel vicitmised by Nicolette and don't want to deal with her. I am happy with my MTN contract and only need a new handset.