I saw the movie when it first came out, and last year, my son gave me the DVD for Christmas...it IS "Soylent Green."
I saw the film on Irish television, either someone at RTE got the name wrong (they get everything wrong on news and current affairs!!), or the film is called by different name on this side of the Atlantic, but then it would 'Green Soylent' not 'Green Soyez'. Most likely I simply remember it wrong.