MTN

Hi, I need assistance. MTN handed me over to an external debt collecting agency last year, I received a call from them saying I owe R4800 which I paid everything now in January, the problem now is when I requested a paid up letter and MTN says I was paying arrears and I still need to pay an amount of R5000, and no one is assisting or advising how I need to pay MTN and pay the handed over company, please assist with this because they are now taking me from pillar to post and I've been calling them and they are not giving me anything substantial. I am writing this for the second time because nobody has gotten back to me, MTN is honestly taking me for a joke.