CLOSING OF ACCOUNTS

In November 2015 I went to pay my last instalment of R31.02, the store clerk requested that I only pay R31 rand, cause 2c has been discontinued. I also requested at the same time that my account be closed. Today I received a sms that my account is in rears with R65.27. When following up I was informed that my account has never been closed and that it accumulated to R65,27 due to the 2c that was not paid. They are not willing to accept responsibility for their staffs incompetency to close a customer's account and insist that I pay the R65,27 before they will close the account. What guarantee do I have that the store will accepts 27c again if I pay this R65,27 to close this account or is this how Acckerman's keep customers on their records for ever?