Bad service: MTN

Good day. I have now been battling to find any satisfactory assistance from MTN since 8 Aug 2018. This was firstly due to a change that was made on my contract without informing me of the full implications and secondly a credit owed to me due to the fact that I was overcharged, for a new phone that I didn't buy. Zukiswa from MTN Social Media Team did reply to me on 12.12.2018 with an apology, asking for further details, which I did supply. However, since then I haven't heard a single word from them again. Contacted me again on Facebook to apologise and up to now, another week later, no feedback.