Sunglass Hut selling faulty sunglasses.

I had purchased a pair of Michael Kors sun glasses for my wife in July. The *****s started coming out and 1 of them had actually been lost in the process 3 weeks after purchasing this pair for R2650.00. After an hour discussion with management of Sunglass Hut I received a replacement pair of sunglasses. Checking the *****s on the replacement pair, again 3 weeks later the *****s started falling out again. Sunglass Hut will not replace this pair for a different brand of sun glasses as I no longer wish to wear Michael Kors due to the faulty model. I had been advised it would take 8 - 10 weeks to have this replaced pair checked for warranty / faulty model and will be advised on a voucher to purchase another pair if I wish too. I do not live in South Africa and now flying back to the EU on the 17th of September. Please advise how I am to obtain my warranty checked sun glasses I paid R2650 for in 8 weeks time. As this is a continues fault of Michael Kors glasses (this pacific model) I do not wish to keep having to use my time to have these repaired every 3 weeks. Especially if I had paid R2650 for this pair. Edgars Sunglass Hut please advise urgently !!!!!