Why doesn't talk to me about a Problem witha credit card and A payment???

I've been trying to buy diamonds, something happened with one of my CC and now I'm not allowed to buy any. I have written many times to find out why YOU won't allow to buy diamonds. all of my cards are working, including my Visa dept card!.. is this discrimation? I had ONE problem with one of my cards and was told that cleared up? so what is the problem?? sever 966 Shurlock