MTN ****med me.

On the 25th of January 2025 I purchased a router online and it was delivered on the 29th of January 2025. When it arrived I tried connecting it but it was not working. I decided to take it take it to MTN store at The reef I was assisted by a guy called Lesego Morake who told me that they can't assist me because I didn't purchase the router at the store. I went back home and decided to call MTN hoping that I will get help,they suggested that I return the router to the store and cancel the contract of which I did cancel the contract and returned back the router to the store,when I got there I got the very same guy who still told me the same thing that they will take the router back but they won't be able to help me with anything nor give me another router. My problem now is that I am receiving statements that I should pay,how do I make a payment on something that I didn't not use and that has never worked?