emergency contraception myth?

So the other day I was at my local Walgreens and I was looking for tampons for my cycle. So we all know that menstruation products are next to family planning. A walgreens worker looked at me and thought I was planning on buying Plan b. Mind y'all I'm 16 and married (also not thinking about kids till I finish my career). The worker was saying that most girls that go to buy Plan B always complain about the price. Of course I was like, Duh their irresponsibility made them buy that. So let's say the workers name is Natalie (made up name) and Natalie tells me this. "Did you know that if you want to prevent an unwanted pregnancy without Plan B, you can? well my grandma once told me that if you take too much Vitamin C after unprotected sex you can prevent the fertilized egg from developing. Did you know that? A lot of people say it's true. Maybe you should try it if you have an unwanted pregnancy right now." BITCH THE FUCK? I WAS JUST WEARING AN OVERSIZED JACKET. I just want to know if people actually believe that works. If anyone knows drop it down in the comments, I know that's gotta be dangerous af. What can too much Vitamin C do to you and your pregnancy?

ALSO NO I'M NOT PREGNANT AND NOT PLANNING.