HiFi Corp has the worst customer service

I have had the worst experience with HiFi Corp Northgate, I guess it's run by a manager Isman and staff who lack knowledge of their processes.

I bought 2 laptops in November, I opened one and didn't like the performance, I returned it and took my card with me, I was told it was a head office refund and I had to fill in some paperwork. They didn't contact me and I forgot about the refund, I travelled and lost my card. I then remembered and visited the shop, I was told they needed the same card they declined initially, I then had an argument and they asked for my banking details to initiate the payment. 2 weeks later I visited the shop and complained, the manager threatened to call security for me because I refused to accept his excuses. I then spoke to the head office manager 3 weeks ago who advised me to get a new card which I did and he promised to call me with a resolution, nothing up until now. I took the new card and they promised my payment in 7 working days, 2 weeks later I am still waiting.

They have had my money for 3 months and they are not bothered