MTN is a ****.

MTN ****med me they sold me a router that doesn't work. It's been a month now since I bought it and it doesn't work. I have been communicating with them via email but even today no response. I even had to cancel the router and I was told to take it to any MTN store near me but when I got there I got a manager named Sharon Hlongwane she told me I need a letter from MTN to return the router and I went back home. Send them an email stating I need the letter even now they haven't sent it. I even spoke to the MTN manager for online she told me I must send her all the emails I have been using to communicate with them I did send them and even now no response and now they are sending me invoices for something that I didn't even use. Where is the justice please help me hello Peter you are my Last hope. Thank you in advance.