Jet Stores reluctance to close an Account

I have been wanting to close an account with Jet that I had not been using for a while, I wrote to them in June to request that the account is closed. I was told I owed an amount of R133.57 and the account would not be closed until I settled the amount. I paid that immediately and sent them the proof of payment. I requested that i am sent proof that the account is indeed closed. i have never received that proof and i am now getting sms's that say my account is overdue with an amount in excess of R400 and payment is needed immediately. I then have been sending e-mails and proof that I had requested for the account to be closed and paid the amount demanded. I get a different reply everytime with each person replying asking for the same things, Account number and proof of payment for a payment made longtime and in the meantime the reminders to pay keep coming and the money im supposedly owing growing. I am disgusted and really disappointed at this level of neglect and incompetence and am worried these amount that are accumulating on my name will mess up my record on an account that should be closed.