Disgusted by MTN Service

I am so disgusted my MTN and their service. I bought a Samsung A2 from Ackermans Sun Village in November 2020. December 2020 the phone started not to work I took it back to Ackermans and because it was 2 sim ports , I was told port 1 only accepts MTN sim and needed to put my other network sim in port 2. The phone worked for 2 months March 2021 it started giving the same issue and had not changed the sim as I was told . I took back the phone to Ackermans and they told me they will take back the phone to MTN and will need to wait for 5 weeks for a response. I submitted the phone box and my bank statement as proof of the purchase because I misplaced till slip and ackermans told me their system does allow them to reprint old slips. MTN collected the phone from the store and its been now 9 weeks and they telling me they have rejected to repair my phone because I dont have the slip even though I submitted my bank statement indicating that I swiped for the exact amount that the phone costed at Ackermans. I mean the phone did not even work for 6 months.