Bad customer service and 8 year old going without Christmas gift due to shops thinking they don't need the clients that shop from them

Sound tech vangate mall had a sale for a Christmas gift for my 8 yr old son to the value of R1200. The product had a manufacturing fault and it was taken back to the store the next day 23 December they refused to refund cash as it was a dedit card which the funds would not reflect immediately. So now my son will not get a Christmas gift for Christmas as they refused to refund cash. I asked vangate store manager for a head office number he said to me I must go Google it. The Mitchell's plain store was called for a head office number and she said it's my problem as the vangate manager called her yesterday and told her and put the phone off in my ear. I have never had such bad customer service in my life