Truworths ****mers

I have settled my account with them on 13 June 2023. At the end of the month I went to close my account but was told there is a balance of R111. 39, how was an interest generated because the account was settled?? On the 14th July I decided to pay that R111. 39 but was told that my account is now R639. There was no valid explanation of how it accumulated. Please help!