Suggestions and "Error"

I sell my heroes 5* star by error, can i recover them ?

And the other question, have any ideas for the heroes and game. To whom should it him send e-mail? ( In spanish better for explain it )

It couldn’t hurt to submit a ticket to Customer Service and ask if they can restore the fivestar covers for you. Worst case scenario is just that they say “no” and you are no worse off.
I am not aware of any Contact information, and I do Believe companies like this are wary of accepting unsolicited suggestions.