Mtn customer service

I have been a customer of Mtn for almost 2 years now on a contract, recently they changed my account from debit to cash payment without informing me, which is okay. The problem is that I ended up having to pay 2 months payment in one month which was September and October. I called countless times to inform them of my payment which has my initial and surname as reference. Of course I was told I should have used either my Mtn number or BA number or ID number as reference. So I spoke to about 10 different consultants and from the 10 2 managed to give me their email address so I can forward proof of payment which I did as per their instructions. Needless to say this is the 3 month after a payment was done and emails sent with proof of payment attached but nothing has been done. According to Mtn I still owe them and now my account is with legal. I'm very frustrated and I am now in a hopeless state. Horrible service, do better by your customers