What if the tour company fails to leave the tour group on time and can't refund the expenses?

did you sign a contract with the travel agency at that time? Have you reached an agreement on how to solve the problem if it is not a group? Usually, if the tour is not organized, the travel agency will negotiate with the tourists for a refund or change the departure date. If it is because of the airline's reasons (force majeure), it depends on the situation.