Croatia is included in the roaming passport, however Bosnia is not.
Bosnia is a 'Rest of World' tariff and you are charged for usage. It's quite expensive...
Although you've been physically inside Croatia you must have connected (probably automatically) to a Bosnian carrier.
(I would recommend always using manual instead of automatic network selection if you are travelling in an area where it's possible to connect outside of it)
I am just another Sky customer and my views are my own even if you don't like the answers
