Unsatisfactory treatment

I have had a TFG account since 2018 while I was a student and I have been able to make payments monthly with no issues and I have been faithful in that regard. I lost my job this year in July and I informed them in August and they agreed to reduce my monthly payment to a minimum, the next thing I saw is my arrears hiking up all the way close to R2000 regardless of my minimum payment that I make that we agreed on. I further asked that they communicated via email because I had phone issues, but they still insisted on making calls and then sending emails of non-payment and being in arrears. My credit record has been affected by this as it appears as though I default my payments. I have a high amount of arrears and it doesn’t seem to be decreasing even though I make payments.