Debt collection ****

I paid, settled my account on 01 April 2020 and they promised that they will send me credit clearance letter confirming I have paid the debt. Since then they are not yet fulfill their promise instead they send some random ladies to call me requesting me to make a payment of R562.12 which I owe. They asked to send proof of payments which I did.

My remaining balance was R2820.35 from R5020.35 standard bank business overdraft since I have already paid R2200, they add R1143.19 for failing to make payments for the past two months and the total outstanding balance was(R2820.35+R1143.19)=R3963.54. I agree with him to split that amount into three months installment which I did paid on record.The debt collector guy whom I spoke with agreed to send me clearance letter and today I phone Cape Town head office and the gave me number advised me to call Johannesburg branch NRS department and asked for debt collector guy or his manager to asks him to attend my account urgently, and when I call they answer the phone and said they transfering me to the guy at NRS department but the call just ended like that.