Bad Product and Absolute Poor Service

Just my opinion and experience I had over the last 2 days with Cash Crusaders Blue Valley Mall. Bought a second hand PC, at the shop it worked, got home, the Wireless & GPU drivers was not installed. Secondly, the PSU cable was faulty. Took it back same day, they repaired it, got home yesterday, the Wireless drivers still not installed, LAN port is dead, and this morning the PC restarts at random. So i ask them politely, please refund me my money, they firstly avoid the subject to repay me, so after getting cross, the owner says that i must pay the money he spent to get the 1st set of problems repaired. I mean seriously, how in heavens name, you sell a **** product, and request that I pay??? Seeing that this was the only way to get most of my cash back I agreed to pay the amount (R350), however, I will in my life, never ever buy any products, new or second hand from this store, nor will i give them a good rating, this is absolutely pathetic.