From Bern there is daily bus to Hum na Sutli most days of the year, the bus goes via Zurich and Zagreb where passengers in most cases has to change bus. Below you can see the buses scheduled to drive from Bern to Hum na Sutli. The bus travel time is about 18 hours. If you are need a bus back to Bern you should buy a discounted return ticket, timetable for the returning buses you can see here.