changing sign in id?

Question

Hello,
I dont know if this is the right spot to ask this question, but I cant seem to get help anywhere else.
Last night I got an instant message when I signed into WL and it said I had to change my sign in ID. When I tried it says I cant change it and says that it cant be changed now.  I am now worried that this isnt real and I was duped into following a fake link.  If this is true, does anyone know what is happening and how it will  affect us? 
If someone can let me know I would greatly appreciate it.
Sorry again for posting here if it is not where I should be.
Thanks