At the moment there isn't one, support can be reached at this link https://cryptolottery.bet/public/helpdesk/
Live chat would be a nice add on but I guess that, requiring someone always always available it would be a bit expensive and can have reason to exist only with a significant volume of play imo. It also depends on answering time of helpdesk : if they manage their request quickly livechat couldn't be amongst the things to do more urgently.