Poor Training On Behalf Of Management & Terrible Service

I have had numerous billing issues with MTN, they have deducted twice the amount of what they should've for my contract, not once, not twice but three times!!! They have stopped my services and said I owe them money, when in actual fact I am up to date with my payments. In January I went to one of the MTN branches to get my contract changed from my sister's name and ID to mine, we filled out all needed information and all sorts of documents to do the transfer, we also provided them with banking statements and ID's - it's now 10 months later and we are still waiting, and due to this I cannot add anything to my contract or even do something as simple as a Sim swap without my sister present as they have not done the transfer. 10 months later!!!