Debit order refund

i bought a product from incredible connection on credit but settled the balance on 18 December 2020. my bank account however was still debited on the 25th of December 2020. i have been contacting them (JDG financial services) via emails and calls since 06 January 2021 to have my debit order refunded. i have sent them the required documents and even a complaint was logged with reference number ***. i still have not receive any feedback or any response from them in this regard.