Nudebt harassing me

Nudebt is really harassing me. My CAMAF account was handed over to them and we had a payment agreement when they called me. I paid all the amount owed by end of Feb 2022. The mistake I made was missing adding my reference number when I made my first payment of 200rand and each time a consultant would call I’d tell them about it and they’d confirm they see it and I have sent POP to 5 consultants already even sent it to some queries and helpsupport email but they still send me messages that my account will affect my credit record. I feel they are *********** and their processes are really bad.