Your client might lose confidence in you and go for an outside realtor. Closing was effected by Asia USA associate asking the co-broking agent to connect with the Landlord and asked her to state her terms. The co-broking agent had an excellent relationship with the Landlord. She had done an excellent job but had given up as she was exhausted too. The Tenant was back in the Netherlands.
Corporate lawyers can be a main source of delays in closure.
The letting agent can only persevere and hope that the Landlord had no better offers. Time is of the essence but corporate lawyers may or may not find that time is of the essence as they still get paid whether the case is closed successfully or not. Sometimes, it is the Landlord who does not give priority to the early reply from the Lawyer. Once, a tenancy agreement takes more than 3 weeks to be returned to the prospective Tenant for approval, the Tenant may have changed his mind and the Landlord has lost a lot of rental. Do not assume that a good faith deposit means that the tenancy is going to close.