Damaged Goods and Bad Service

My husband purchased a pair of white gold tanzanite earrings for me on the 6th of February 2015 and I wore them yesterday the 10th of February 2015 for the 1st time and the stem broke off . I called Cresta NWJ this morning to speak to the manager and the lady who answered said that she was the manager Innocentia . She firstly did not even apologise that I had an issue with the earrings and didn't even allow me to even finish speaking but cut me off by saying that I should bring the earrings in and they will send it to the head office and only if they say it's a factory issue my earrings can be replaced or fixed ! This is not the 1st piece of jewellery that I have purchased from NWJ Cresta that broke I have a tanzanite and diamond bracelet that also has broken .. Can someone explain why the jewellery is so weak !!! This is really disappointing not just because of the broken jewellery but the poor service !