FNB, is this even legal?

i must insist that I am very mad at FNB. I had a premier cheque account with them. I dont how the calculations worked on that account because it would not reflect on my account. I then decided to stop using the account because it was very confusing for me. I asked FNB to close the account and they refused. The account has been accumulating charges and today in the midst of Covid19 with no cer*****y of employment I receive a message saying the account is coveted to residual account. What nonsense is that! I demand that FNB closes that account ASAP! It was your bank's miscalculations that led into this situation and in first place and your consultants cannot even explain in layman terms how the account works!