If a handling company told me that it's "not their job to inform me or to liaise with crew conserning passenger arrivals, transport to aircraft" etc etc my first phone call would be to our head office explaining why we should never use said handling company again.
As long final already mentioned, we often get charged "Executive lounge departure / arrival €xyz x number of pax", "VIP transportation", "Passenger departure handling" etc etc. If for those charges they feel they can't give us a call to make sure we are ready for the pax, or just to give us a heads up, then our money should be going somewhere else. Having said that in most cases I will be in the terminal or lounge meeting the passengers when they arrive, but in some cases this is not possible.
CP