MTN Terrible billing errors no answers

After our last experience with MTN and them reconnecting us , we recieved wrong billing again. We have emailed repeatedly customer care and have no reply. The one no ending 488 is 499 per month yet on 14th feb 2020 we got billed an additional airtime and internet same as package which was not asked for.... this two days before our contract billing due to go off this is about nearly 150 additional which does not add up.... My wife does not even remember if she received it as she uses that no very little currently Also monies paid to MTN in march is not reflecting on statement...