Swapped My Diamond

My 10ct white gold, 1ct diamond ring was given in on the 6 November 2017(NWJ. Cornumbia, Mount Edgecombe) for resizing it has 3 large diamonds and small diamonds on the sides. I was told that I can pick up the ring on the 9 November 2017, on the 8 November 2017 I received a call saying that the jeweler is sick and the ring would only be ready on the 13 November (one jeweler for such a reputable company?). I picked up the ring yesterday, when I got home I noticed that one of the large diamonds is yellow in color, I know that the diamond has been swapped, I called the store and the assistant says its not possible (I know my ring and even a fool would tell the difference in color). I have lost out and would definitely not get my money or diamond back so I just want to make people aware and I would never recommend NWJ to any of my friends or family and will definitely pass this experience around. I AM DISGUSTED WITH NWJ !!!