You have to look at the agency contract to find out what he promised to do, if the agent did not abide by the agreement/authority then they can be sacked
Change the locks anyway because you have no idea who else has the keys.
If the agent wants to claim the lost commission they have to take it QCAT
QCAT are not easy to deal with due to the abdominal bureaucracy of the department, but it is all you can do just make certain that you have all the facts
Ultimately it is usually a case of paying what’s necessary and moving on.
When they next choose an agent get more detail on the authority with penalties for non performance
