Poor mtn service

I am so frustrated with MTN, I upgraded on my mtn contract on the 14th of February 2020. At a I store because mtn did not have the device I was looking for and they could also not get it, so I was on a mtn sky contract which was R1469,00 a month, I got a new device and downgraded on my package to a mtn made for you package which was supposed to be R1389,00 a month with the new device, mtn has yet to downgrade my package to the made for you one. They are now charging me R1900,00 and something rands per month, I have a contract that states my downgrade on my package and the new installment, the are refusing to sort this out, I phone them on a weekly basis, take at least 2 hours out of my day to spend on the phone with them, just to be transferred to the next person to explain the story again and again, I am refusing to pay this R1900 a month until the problem is sorted out.( I have been trying to sort this matter out since March) mtn has cut my phone line numerous times due to “non payment “. They are also threatening me with legal action, I don’t know what to do anymore, I am fed up with this ****!! Mtn has also in the past, cut my phone line 27 days after the last payment that they received, so I payed my bill on the first of feb and they cut my line on the 27th of feb. I am tired of phoning them! A nice excuse I had about 3 weeks ago was the, no our legal department doesn’t have phones... when I asked to speak to someone more senior. I phoned again on Tuesday this week, and someone told me that the matter will be resolved and that they will phone me back, it’s Thursday today, still no ability to make a phone calls , I have once again been threatened with legal action today but still no phone call from mtn. I need to be able to make phone calls! MTN South Africa... please advise... regards.