Hi, I am from Ecuador I hold Three month F visa, i would like to stay longer.

I'm pretty sure they won't accept a renewal application earlier than 7 days before your current one expires. I've had multiple F type extensions and this has always been the case, so you'll probably have to wait until August.

Usually, when you extend an F type inside China the only option is a 3 month single entry one, but I could be wrong since the rules seem to vary from province to province and city to city. 6 month multiple entry F types are usually given when applied for in your home country (maybe a neighbouring country like Vietnam. I don't think you can get that kind of visa in Hong Kong anymore).