What is the ruling on receiving goods from customs that are not my own, knowing that my goods were lost by them, and the substitute goods will be confiscated if I do not receive them within a week?

This bag you took in place of your own has two possibilities:

1. A bag awaiting its owner: You are not permitted to take it, as it is someone else's property. It must be returned to its owner if possible. Otherwise, it, or its value, should be given in charity to the poor. If you later find the owner, he is given the choice between approving the charity or taking the value. 2. A confiscated bag: The confiscation must be examined. If it was confiscated unjustly, then its ruling is the same as the first case. If it was confiscated justly, then there is no objection to taking it in place of your right.