Poor customer service

On Thursday, the 3 January 2019 I had called at the MTN Randburg Square store as my handset would not charge. On the Monday evening, it gave me an error message that my charging port had water in it, which to my surprise was extremely odd as the phone was never exposed to water or a damp area. A week prior to that it did the same thing, I simply switched the phone off for the night and it worked fine the next morning, hence I went on as normal, because we were not at home. On Wednesday evening, 2 January , as soon as I plugged it in to charge, the same error popped up, as a result I could not back up my phone because I had 8% battery life. The following day the staff at MTN plugged the phone in to charge and it started charging immediately and in a very unprofessional, abrupt manner refused to book the phone in. I insisted that they do, as this had occurred three times already. Strange though .... if it didn't have a problem .... why would I be sitting without it 49 days later!!!! Furthermore, I would like to indicate that this is not the first time that I experienced a problem, in June last year my handset was taken in and replaced due it just switching off. I must stress though that the difference is that I got regular feedback from the store as opposed to now AND I do not have a spare phone lying around to use while this issue is being sorted. On the 26 Jan, I popped in the store since I was in the area and they had no feedback for me. they called me on the 29 Jan saying that the warranty was approved and that they were waiting for the handset. In the meantime, I have paid MTN for a handset which I have not had for 49 days!!!! I have requested changing the model of the phone because this particular phone is obviously troublesome, I was told that I can only do that after the THIRD occasion of experiencing a problem!!! Can I not be refunded for the rental of this phone? Can I not change this phone, I do not want to have to go back and forth with, because it is evident that this particular model is troublesome? Can somebody tell me how much longer do I have to wait for this issue to be sorted out!!!! Can somebody give me feedback, whatever has happened to CUSTOMER SERVICE!!