Incorrect ring size & Service Complaint

I am very furious and disappointed with Sterns. My fiancé brought an engagement ring at Sterns (Mall of Africa) and for him it was very embarrassing to ask the big question and the ring does not fit and you cannot resize it. I am furious he went to Sterns Alberton City yesterday and they told him Sterns Mall of Africa should have given him a loyalty card and they should have told him that the ring cannot be resized due to the fact that it is custom and can only be given in one size. Now I'm engaged and he had to tell me that I cannot get the same ring that he gave to me which he proposed to me with. Its an embarrassment for my poor fiancé not only can I NOT resize my ring but now I cannot wear any ring. He spent a lot of money and this happens it is not right. He also posted this issue on their website and told Sterns about this issue and he went into the store and nothing was done.