There is already an agreement on the house payment in the house sales contract. The down payment can be made to the landlord first, and then the final payment can be made according to the approval time of the provident fund center, the loan time and the transfer time of the three certificates. This is no problem. You don't need to write an iou. This is unnecessary. Just stick to the contract. I don't know if you signed a contract with an intermediary company. The formal contract has a clear agreement on the payment time of the house payment.

Provident Fund Center, Housing Authority, etc. Everyone has a commitment to a working day. I guess you didn't find an intermediary to handle it, otherwise these promised things would be handled by the intermediary. I suggest you consult the local intermediary company, and what is the time.