Terrible customer service

I returned a ring I bought at sterns mitchells plain promenade on the 6th December 2017. The ring is for my fiance. We were out having supper. She came back from the toilet and noticed the stone popped out of the ring. I returned the ring on 2nd February 2018. Received a response after waiting longer than a month. Probably about 6 weeks. I was told the ring is ready to be collected. I get there and the stone is still not in the ring. I blew off most certainly. Store Manager approached me and told me the specialist says the ring is badly damaged plus it's not a R5000 ring so I can't expect much from a ring under R1000. I then told her I could've gone to a cosmetic store instead and saved the time and hassle of buying one at Sterns.

The manager then took her ring off and asked me how long do I think she has that ring and it has all stones in. Like really??

I was told I'm going to need to pay R180 to have the stone replaced. I refuse to pay that money because at Point Of Sale. I was told the Stone is covered and ring is covered. The sales lady gave me examples like should the Stone pop out or should the ring bend. A repair will be done. If not replacement will be done with a ring of the same value.

Store manager then tells me rings are sensitive items and even bending down to tie your shoelace could cause the stone to pop out due to the pressure of the finger.

Who sells such low quality products and charge a fortune. Peter, I can tell you. Sterns does! The manufacturer is Duncan Jewellery.

I received the worst customer service! I was made felt like a child that is being reprimanded for a fault.

What can be done about this?? My fiance needs her ring.