Makro online no response on failed refund payment

My husband ordered a gaming chair for our daughter on Makro online. The online transaction took the funds from his debit card. We had to call numerous times when delivery would take place only yo find out almost 10 days later there was no stock. He called makto customer services and they said he would be refunded. He called back 8 days later as there was no refunded amount from Makro in his account. He called customer services again and together he and the agent found out that the refund payment to him failed. He was then told to email a copy of his ID and proof of bank account. That was a week ago. No response from Makro.