Telkom

I got a router on contact with telkom in December 2018 and the experience had been horrible from on set. First my contract deal was wrong of which they managed to fix after talking to 6 different people. Then I was invoiced incorrectly and when I called they told me that it was an error from their side and they will fix it.i was then promised that my invoice for March will be less because they overcharge me in February,then receive invoice for March and I was still overcharge and the amount is not the same as February. I then called the call center and I was told that they don't understand what's wrong with my contract and that I should send an email to the billing department of which I did with no response. I just need help.