Thousands of rands for what seems to be ****

I purchased a ring (item description ***) which is silver with Sapphire stones for the amount of R3 499-00 on 24th February 2015. The ring was too small and I took it to American Swiss (The Crossing, Mafikeng) for resizing. After waiting more than the 7 days as promised I finally received it on 25th March 2015. On 02 April 2015 I returned with the ring as it seemed to be turning black which seemed like the silver was coming off and the spot where it was resized was a goldish colour (notice that this is only after having the ring back from resizing for 9 days). The lady at the store then cleaned the ring with some liquid and it seemed fine. She advised me to purchase the jewellery cleaner and cloth. I then only purchased the cloth for R219.00. After 3 - 4 days the ring starting turning black again and cleaning it did not help. I am very disappointed and feel that I have been ****** of thousands of rands for something ****. How can you purchase a ring for R3 499.00 and after just a few days the silver comes off? I would appreciate assistance with this or a ring which is not **** or my money back. I feel ashamed to give people my hand when they ask to see my ring.