OP, you are betting at a 3.8 multiplier on a site with a 5% house edge, giving you a 25% chance to win each bet. Losing 5 bets in a row is hardly some freak statistical anomaly. Also, your 5 lost bets comes to grand total of 811 satoshi, which is less than 7 cents. I hardly think a site which is giving out tens of thousands in prizes is scamming you for 7 cents. 
Still, freebitco.in is provably fair, and has a page which explains how they calculate your roll which you can independently verify yourself. If you have proof that this is incorrect, then please post it.
I used them for autobet because I had this formula worked out where I had a very good chance of beating them.
No, you didn't. There is no such thing.from something that is 50/50 chance.
There is a 5% house edge, so it isn't even close to 50/50. Also, if you are making only 50/50 bets, then chances are you are using Martingale, which is a strategy famous for busting newbies who don't understand probability.Still, freebitco.in is provably fair, and has a page which explains how they calculate your roll which you can independently verify yourself. If you have proof that this is incorrect, then please post it.