Geo targeting and domains rotations

Hi, im trying to find some solution..

we are big multibrand casino online that working world wide
for example our main domain is casino.com and we have another domains casino-a.com casino-b.com for countries that blocks by ISP.
in our main domain there is hreflang for example casino.com point pt-BR to casino-b.com but google still index casino.com on BR.
its look like google ignore the hreflang and prefere the main website instead of the website that is only for this country.

i tried to add some geo targeting signs, for example h1 title and meta title "Casino Brasil" etc.
nothing work and i can make google to show the casino-b.com instead of casino.com in brasil for example..

its complicated, we have alot of subs websites for each country that sitting on different domains..

im trying to get some ideas or maybe solutions from our amazing community

thanks in advance.