It's quiet possible. They would be flooded with complaints if these are proven to be true. I recalled back then something also similar happen to mine, but i didn't really made it a big of a deal because my stakes are low to begin with, but in this case I guess the OP lose quiet an amount. If there is still no reply from them, might as well consider them cheating the OP that's what i think.
Even if that is true, I am not sure they will get many complaints from people who play on their site because I think only a few people who have that experience.
So maybe some people will report this to the supports, and ask them to check it to find if there is something wrong or not that happens in the site.
I suggest OP move to another gambling site because of that bad experience because I think that experience will make him trauma to get another bad experience.
Once again, it is an important lesson for him, and he should not use big money to play gambling because if he loses all of that money, he will not have a big regret, and maybe he can playing other games.