bad service and ridiculus service fee

Good Day

I recently had a cheque account with ABSA and due to non satisfaction with their service I had a problem I couldn't use my internet banking and I sent them an email and they said the case was closed without even helping me none assistance at all I decided to open another account with a different bank and now I'm getting emails for different attorneys telling me that my cheque account that I had with ABSA is in arrears close to 6 450 and I need to pay for it and I have being using it from June and bank charges are not that much monthly so please can somebody please explain to me what is going on here and I did sent an email telling them to close that account and even called customer service and was advised that I need to go to the bank to close it as they cant do it over the phone so whose fault is it