Ruined what should be an exciting time

My fiance bought me my engagement ring in January 2015. Firstly the diamond had a blemish in it and with the quality specified in the sale it should not have had this flaw. It was sent in to replace diamond (took longer then promised with this only being communicated to me from follow up calls done my myself). Then the clasp broke, twice (both times took longer then promised with this only being communicated to me from follow up calls done my myself). After the third time the same clasp broke we established that it was a weak design and was told by the store that they would discontinue that design because I was obviously flawed. I discussed a new design with the store and it was sent in for alternations (once again it took longer then promised with this only being communicated to me from follow up calls done my myself). When it came back the design was different to what was discussed and agreed. We then sent it in again to be changed to the design discussed but the outcome was once again disappointing. Agreeing to try once again with a new design, Donatello moved stores and I have I have not been able to contact them for over a week now. My Donatello experience is HORRIBLE!