Incorrect sales protocol & refund

Hi there, trust this finds you well, i recently purchased a Dxn pro usb18xlr controller online, and collected it at village Square, I found it quiet weird that the guy that was assisting me didn't test the device nor ask for my identity, he simply gave me a charger and told me to return it if there's any faults for a repair or refund...

I purchased this via mobicred on the 15th of March and collected it on the 18th of March, on that very same day when I got home I used one of my usbs to test the device and it was flickering and none responsive, I tried both USB ports and nothing happend.... I quickly what sapped them on their whatsapp number to alert them that the device is not working and I will be returning it, they did not respond.

Today on the 21st of March when I get to the store they tell me they need to send it in for assessment and I have to wait 21 working days, I quickly alerted them that you did not test it and we alerted you the very same day that it's not working... As the Lady was printing a "refund slip" that was written repair.... She uttered that this device hasn't even been removed from the stores inventory, only then we received a message alerting us that the device has been collected.

My question is wouldn't it had been easier to just cancel the order and release the refund as it say on the system it never left.

I'm very much disappointed with my experience and would like a refund as soon as possible as I bought this item for my gigs that happen every week, every second I wait is a meal taken away from my family, by people who do not know how to follow protocol yet seek us to follow proper protocol.

Please kindly advise where to from here as this is not my fault but the store assistants. His name is Brian.

Regards Thato