Disappointed delight *******

I’m very disappointed in this account I recently opened up n received credit to purchase a cellphone the interest rates was Ridiculously high n forced to pay for insurance which takes even longer to pay off. I settle 5th Oct 2024 paid R10901.80 in full . The balance was zero and wanted to close this account. To my surprise I got an sms stating I need to pay 219.01. It’s interested that was built up from a zero balance. How can I be charged interest fee when I settled this account I refused to billed for something I settled and disputing this amount and want this account to be closed.