Mtn is harassing me for the phone that was brought back

Was given one SIM phone although on the invoice it was dual SIM, brought back the phone to 14th Avenue but still I am billed, now they sending smses saying they will send it to my bureau. Why am I billed if the phone is not with me and I have never used that phone. Firstly I tried to call to complain about the phone since I bought it online through Mtn consultant Lalisha Munien

Telesales Agent

C: ***

I was told to take the phone to any MTN store , I took the phone to MTN Ghandi Square they were busy looking at the phone saying they have never seen one SIM Samsung Z flip 4 and later after 30 mins they can't take it due to system being offline nationally imagine my lunch break was wasted.

Because of the long hours I work , I knock off late so that was my only time to submit they gave me a paper just to show I was there, was told to use it as prove . So I took the phone to MTN the Glen Sunday Monday was told they cannot take it it's after 10 days the 10 days was on Saturday and was working, Friday MTN Ghandi Square told me MTN is offline nationally. MTN The Glen referred me to 14th Avenue to take the phone there was helped by a Male Consultant Mafu Zolile , he took the phone and said it will be taken to warehouse, come month of December I was billed for the phone and I reversed they debit order and paid manually for my other SIM card and called them I was told the phone was not cancelled and was transferred to cancelling department and again I am told I will be transferred to billing department when I try to talk to them after a long hold they drop the call. Now I am getting smses that I should pay or they will send the information to the bureau.

Mtn why are you making our lives a misery. I don't have their products with not have I used the phone but why I am billed. I have all the paper work even the 14th Avenue one. Please help asap, it will affect my credit report.