Pillar to post about downgrading / closing account

I have been with FNB over 20 years, I had a credit card which I paid off and closed but they left a trap in overdraft facility so it seems. I asked about some small charges in my account via secure chat and couldn't get a straight answer because in my knowledge I should no longer be paying for some credit facility since my y credit card was paid off and closed. Fast forward to few months down the line with no income, I tried freezing or downgrading the account on the app to avoid monthly fees despite not using, but it became impossible, I then resorted to the secure chat which was useless, I was told I could not freeze downgrade or have to go the branch. Now after visiting the branch I was told the account automatically closes after 4 months without use but mine could not be closed because it has an overdraft facility and now it has been handed over to debt collectors. It's disgusting, and cruel to us consumers FNB just wants you in debt paying and paying and if you don't you start getting demand letters...maybe posting on Hello Peter will get their act together. Why is it not possible to downgrade or freeze or close account when become unemployed to stop incurring monthly fees? Why must one be charged monthly fees if no usage for months?