From what I see they have an U.S based address  and a phone number , first you should try calling that U.S number , and second you should really consider reporting them to the authorities , there is 0 reason for you to give them half the winnings , and they most likely won't do it as they can simply keep  the 30 k $ .  So your best option in this case would be to contact the authorities and report them , aswell as that telegram manager for extortion.