Refund squabble

I bought online on the 17th of March 2020, the payment was successful however I did not receive the invoice. n the 18th of March 2020, a personnel from Makro online phoned me to say that my initial order was accidentally canceled and a new order was placed on my behalf. The product was delivered and I returned it because it was wrong. Due to lockdown it was received and assessed in May 2020 and in July received an e-mail that I am due for a refund but they will need the invoice but I told them that the invoice was never sent to me and I sent the bank statement so they responded on the 08th of July 2020 that the statement that I sent starts from the 26th of March 2020, I must send one where they will see the amount. I sent the 6 months bank statement where the transaction is reflected and still today the refund hasn't been paid.