Bad quality and the worst customer experience ever!!!

I bought an engagement ring in December 2018 and Proposed to my Fiancee on the 7th of March 2019, on the 9th March we seen that on of the stones has fallen out. We took back the ring on the 11th of March 2019 and the ring has been sent for repairs, last week i called to find out what the status of the ring is and was told to collect the ring as it has been repaired. Julia opened the ring up from the packaging and I inspected it just to find that another stone has fallen out. They told me that the matter would be escalated to Ramona who deals with these queries as i dont want the ring because it has a defect. I was promised feedback from Julia on 12th April or 15th April for the latest. I had to call them this morning and spoke to Julia again and she promised that she will follow up on it and call me back, this call was made roughly 10:30 this morning, I called again just after 2pm and they still dont have feedback for me. The quality of the rings is ****. How can a brand new ring's stones be falling out continuously. I want a refund, i dont want the ring to be fixed as its defective.