MTN - Poor customer Service

I am very disappointed. Was notified and given a tarrif hike of 5% , however received a bill for a 13% increase. I tried in vain for days to contact 135, to eventually get through and log a ticket...only to have the ticket closed off the following morning with no feedback.Trying to contact 135 again for feedback and you either stay on the line forever or the call just drops. Now I am stuck with an increase that's not valid for the remainder of my contract until I can get someone to resolve...even the complaints email line or the app is of limited to no use to help.