Is it permissible to reduce the brokers' commission from 5% to 2.5% after the agreed-upon period for completing the transaction has passed, and given that they exerted no effort beyond initial guidance and refused to intervene in expediting the procedures?

If the agreement or custom dictates that the intermediary is entitled to a fee simply by indicating (the deal), then he receives the full percentage, even if the completion of the transaction is delayed. However, if the agreement stipulates the completion of the transaction within a specific period for the entitlement of the percentage, then he is not entitled to the full amount unless that condition is met. If it is not met, then he is entitled to the customary wage (ujrat al-mithl).