Missing Diamonds & Ring turned bronze/copper

I purchased a white gold ring in December, then it went for resizing I got the ring back a month later. I did not even wear the ring and 4 days after I collected it the ring turned bronze/copper and there were 2 missing diamonds!!! For something so expensive thats what happens to it, its like they are selling **** jewelry at 10 times the price. Then anyway it went for fixing AGAIN at the beginning of February and I am still waiting for the damn ring!!! They called me on Friday to say sorry but they experiancing problems with the jewelry factory and they need more time or they have to make alternative arangements! That is not my damn problem. I want a refund and I will purchase jewelry elsewhere!!! Please keep the ring!