1. Why did you assume that they came in Pairs? Did their description lead you to believe this, or was it wishful thinking?
2. When did you send the e-mails? How long between each mail? Did you give all the necessary references for them to be able to identify your order? How long did you give them to make a reply?
3. How did the breakage occur? If you broke it yourself, as you described, why do you think that they should replace at their expense?
Please don't think that I'm being negative, but I am asking you to think carefully before you answer.