MTN- useless in billing messing up with people contracts

After having multiple contracts with MTN for a few years now, I've recently been double billed for one of my contracts , a 24 month LTE contract without my consent or notification as to why I was charged double suddenly, can't get through to anyone when I call MTN and I have emailed MTN , I was told it was escalated to billing but till date nothing has been done 4 days later. This will motivate to cancel all 3 contract options and in future advise people to not use MTN, as there seems to be people who activate services on contracts without people's knowledge as well billing them incorrectly without any resolutions. If this continues I'll have to take it further.