Interest Charged on 6Month Interest Free Account

Edgars Card E-Statement - *** On the 5th of January I purchased a Huawei on my 6month interest free account. Four days later received an SMS for payment. I responded to say payment is only due 31st January 2021, which I paid. In April I visited Blue Route Mall in Tokai, Cape Town to query the interest charged to my interest free account. The consultant promised it will be corrected, but according to my latest June statement, it still hasn't been corrected. The total interest due R256 +R26.22 (SMS). A balance of R24, since November 2020, also never investigated after a few unanswered emails and enquiries in store. I have also attached an excel spreadsheet to assist with the investigation. My account will be fully paid end of June 2021, *minus interest *minus sms charge *minus Oct/Nov 2020 outstanding balance.