Debit without Authorisation

So, my accounts are closed since November 2015. Now, In Feb I get an invalid invoice for another R 130. I send the invoice on a mail to their customer service centre to get them to correct the records. 3 days later, I get a mail indicating the call is closed. Without any advice or discussions with me. Now, after another week or so, I check my account and see they have indeed debited my account!!!! No service at all. I am so glad I am no longer your client as your service sucks - please update your records as I no longer have any contract with you and I WILL take legal action for invalid debits to my account