Unacceptable return policy

Last year I have purchased an Asus core i7 PC from Dion Wired in Woodlands Boulevard Mall in Pretoria East. I am very reliant on my PC as I do programming both at work and in my studies. I am also regularly on Skype for business meetings. This is were my problem came, the PC's sound completely kicks out after a loud noise. The PC has been taken to Dion Wired on various occasions under warranty and sent for repairs at Incredible Solutions three times. The manager told me, after the second incident, that they replace or refund the unit after the third incident. Now that the PC is returned for the third time with the same problem, Dion Wired absolutely refuses to replace or refund the unit. I cannot accept the PC back, as the PC and Dion cost me so much time lost in my work and study time, which I cannot get back. Therefore I cannot accept the unit back and continue with the same problem. Dion Wired are very reluctant to resolve issues after you have purchased a unit from them.