When I try to change my security questions, I don't get the Email thus I can't change them.

I mean, whenever I try to buy something I get asked for my security questions, which, I don't know, but the problem is when I try to change them. I know my mail and my password and everything but when I click on the link to change my security questions there's this message that pop's out and says "A message to your Email has been sent" but I never get "such Email". I've been trying to solve this problems for a month now, tried everything but i came to the conclusion that i won't be able to buy anything without help or tech support, idk... Anyways, I need your help guys, I'm from Mexico (if you have the mexican Apple care center phone number). Well... THANK YOU and I hope you have the answer to my problem, would appreciate. 🙂