Poor customer service/ repairs

I bought a ring a month ago at American swis and I had a signing ceremony on the 20 Aug 2021, that when I started using the ring 2 days later the stone fell off I took it to the store (Galleria) and they sent it for for repairs and this past Sunday I noticed the same stone has fallen off again and today I took it back to the same store, and they said they had to book it in for repairs again but my concern is it the same stone so I asked to take another ring and pay in the difference, they refused. The lady said she is following procedure and it not my decision to make as a customer I will have to wait on them as the store to tell me if I can take something else that is when the ring get back from the repairs.

Mind you this ring was bought on the 14 August started using it on the 20th August today it is 21 September....

Please assist.