TFG (American Swiss Lichtenburg) review: To be reimbursed or be given a chance to choose another ring.

I'm typing here with heavy heart I was mistreated by a store manager at american swiss lichtenburg branch. I bought my wedding ring in august 2021, within the first month my ring started to be dull, and had a blackish discoloration. I went to the store in question and was assisted by the store manager. I'm not happy with how she attended my query, I was told that the reason it's changing colour it's because of the sanitizer. My ring description: 925 za, I think it's 5 ct, cluster ring. I hate my ring because I cannot wear it without having used jewelry cleaner on a daily basis. Please help. The store manager chased me and told me there's nothing she can do about it, after they exchanged the ring 3 times already. I've always trusted american swiss and the quality of their products until my recent experience... My ring is only 6 months old and it's already giving me headache. Tfg headoffice please intervene.