irritated customer trapped in a contract with a ****py phone

Went to MTN in pavilion 10 days ago for a sim swop, they have informed me 3 times that it is successful but I still don't have my number. They offered me a phone and gave me a different one. Got home and saw the error but was informed that I cannot return the phone after 1 day. The phone was sealed and I had not even used. Sent 3 emails to Fazila Nzama and Noluthando Nzama still no response