No service delivery

I received my new phone in March and it gave me problems the same day. I spoke to a lady called Ellen she assist me with the phone, she asked me to take it to the nearest MTN, when I went to MTN they told me the M5 was recalled. I should ask them to collect my phone. Which I did, up to now I still don’t have my phone back this will be the second month I will be paying for something I don’t have. I also wanted to cancel my contract with MTN but they have assured me that they will try to improve the service. I am sending emails and making phone calls and keep on hearing that someone will phone me back, but up to now nothing is happening. I would like to know what is happening cause this is really annoying me cause MTN is treating their customers like beggars, but claim to be the best in South Africa.