Ring turning black after a month

I cannot believe the experience I have had with Sterns. I will never step foot in there again. I am not one to complain and turn to social media but I am not getting any help from Sterns Galleria. My fiancé purchased an engagement ring on the 8 September 2024 and proposed in the 27 September 2024. On 3 November 2024 I took my ring in as it turned black, sterling silver should not turn black so fast. The lady I spoke to proceeded to tell me that it was my fault as I use harsh chemicals, I immediately told her that I do not. She also told me I should only need to clean it once or twice a year. It had only been a month. So she took the ring in to be recoated and I got it back on 11 November 2024. I took the ring back on 3 December 2024, which is not even a full month yet and it turned black again. I explained to the sales lady that I do not use harsh chemicals, when I shower I place my ring in a glazed clay bowl and some nights I place the ring in my ring box given from Sterns for safe keeping. The sales lady turned around and told me that the ring box has chemicals and can affect the ring and me placing it in the clay bowl also damages it. As she cleans my rings she tells me the ring has been heavily exposed to harsh chemicals. I told her no it has not I have barely worn it for a full month after being returned to me. She then told me I am suppose to clean it every two weeks. That is not what I was told by the other sales lady and other jewellery shops. Anyways she has taken it in to be assessed. When I want a refund they tell me no, not after I have worn it.