You are from the Dominican Republic if I recall correctly?
Too bad WES cannot help you. They appear to be the most widely used agency for evaluating high school credentials for college admissions; they are very transparent about how they operate (e.g. they will give you access to their grade and degree equivalency tables before you pay them any money); and they are more generous when converting grades than many of their competitors.
I’d recommend you stay away from ECE. I have heard multiple complaints that ECE converted grades “at face value” from applicants who later got a second evaluation from WES with much better grades.
I don’t know which specific organisation may have experience with your home country specifically, but this list may be helpful if you haven’t seen it already: http://www.naces.org/members.html