Not getting my phone back after multiple attempts

I have booked in an LG G5 on 1 Nov 2018 (still a few days left on the 2 year warranty) with clear instructions what was wrong as well as to check if it can be fixed. IF there is additional costs then they must first let me know before fixing it. Almost two months later I call again to find out what is going on, only to be told I owe them over a R1000 for the repair costs. This was never my instructions and I told the consultant as such. The then told me they will get back to me which never happened. After multiple calls from my side I was told that they were wrong and would sort it out immediately and send the phone back. It is now 4 months still with no phone and I don't know what is going on. MTN this is extremely bad service and WILL open a case of theft against you if I do not get my phone back ASAP. You were in the wrong and now I have to wait for a phone and sit without it.