No feedback, no answers

I handed my phone in at MTN Vereeniging on 23 Dec 2017, after it stopped working for the second time in a month. I gave them time due to the fact that it was holidays etc, and then I started to call to find out how far my phone repair was. The previous repair for the same problem took two weeks. I was able to contact them with success, after which they rep**** they will get back to me. I phoned the next day and was told that they were trying to find out where my phone was. Promises again of getting back to me was made but to no avail. Ever since then I have not been able to make contact with the branch at all. There is no answer ever. I work in Alberton, and by the time I get home in Vereeniging, the branch is already closed. Which means, with them not answering their phones, I have to go to the branch every Saturday to again get promises of contacting me, which never happens. My biggest issue is that the phone's guarantee will expire the day after tomorrow, and not having the phone back yet, I will not be able to send it back in if the same problem occurs again IF and WHEN i do eventually receive back my phone. Can someone please contact ME to sort out this issue ASAP?