MTN SA misery!!!

I bought an A50 samsung on 27 April 2019 @MTN Menlyn Pretoria. On 16 September 2019 the phone did not want to switch on. I took the phone to MTN Columbine square in Johannesburg and was told that the phone was going to be booked in for a warranty assessment (as the phone was still within the 6 months period) and if it passed that I was going to be given a refund or a new device. On the 3rd of October 2019 I was told to go collect the phone, to my surprise I was given my old phone and repairs had been done on it. The MTN personnel said that they did not understand why it was repaired and not assessed as initially booked. They then told me that its I either took the repaired phone or they were going to have to send it back for an assessment which was going to take another 15 working days. I then decided to take the phone as it is very inconvenient being without a phone. Two days later, 5 October 2019 my phone froze, the LCD was not responding and I took the phone back to MTN Columbine Store. To this day I have not received my phone. Whenever I call MTN, the manager tells me that it is Samsung that is holding up the process and not them. When I tell him to escalate the matter within MTN he tells me that that is not possible and that the only thing that I can do is to call Samsung call center.It has been more than 2 months without my phone but MTN still makes the debit order deduction. I am leaving the country month end of November 2019 for the US and need to either have a new device or a refund as I cannot cannot continuing paying for a device that is not in my possession. Please assist, I feel like my consumer rights have been immensely violated!!!