Have you tried the forum on this site?
They speak of Hamansi. http://www.belizenet.com/
We stay nearby Hamansi when we go to Belize and I don't dive so I can't give accurate information, but on a stroll past their resort, it looks nice.
There are several resorts along that strip of beach, one can stay anywhere and still do a dive with Hamansi, just walk up.
We love that area.
It's like our second home.