HiFi Corp - Kenilworth Poor service

On the 30/01/2021 I went into the Kenilworth branch to purchase 2 x Ultra Link units. While at the counter purchasing the items, they had a security lock around the 1 unit that they unlocked to hand it to me. On receipt I noticed that the plastic was removed and the seal was broken. I opened the box at the counter and found that this unit had been used and was maybe returned, but this was not a brand new unit straight from the shelve, as Paid for. I immediately asked for a refund, as I was not going to leave the store with a second hand unit. While waiting for refund the gentlemen in front of me was returning a laptop that he purchased and when he went home to set it up, it was already signed on and registered to another person, so was also not a brand new unit sold by this branch. I called the head office as I have not received the refund yet and was told that I takes 14 days to refund a client. It have been 20 days now and I have still not received my refund and Head office keeps saying that they will call me back and they are not calling back.