Ackermans Account was settled and requested to close it in March, today it is still open and getting harassing eStatements saying i am owing

I am currently having a confusing service from Ackermans and their Customer Service. I have paid the account in full in March and advised them to close it. On that same month when the account was paid and settled, they came back with an eStatement saying i have installment to pay. Since then i have been sending emails to query why the account is still not closed and why it keeps on accumulating even though it was settled. Everytime time i reply to their emails, i get same reply to forward detals. When i do, again i get another reply asking exactly what i have emailed. I am at the stage where i even regret having opened an account with such company. Ackermans account has been paid on time every month but this service i am getting it is so unprofessional and uncalled for. I have paid all what was due and instructed them to close it. Surprisingly even today they still send eStatements saying i am owing. Maybe in this platform they will be in a better position to tell everyone why they didnt close the account and why is it still open today, i find this harrasing and unacceptable. I have never purchased anything since then