Sifiso at MTN Retentions is rude and unhelpful

My reference is ***. I called to cancel my contract and spoke to Sifiso in Retentions. He insisted that I will lose my minutes and data when I move to prepaid. I challenged this because I paid for them. When it became obvious that he can't do anything for me I asked to speak to his manager & he said the manager is not there which I found to be rather convenient for him. He was rude and condescending and would not put me through to a manager. I want to go to prepaid with my minutes, & I want Sifiso to be disciplined for his rudeness.