Dear Ms X:
With reference to your fax dated 7 May 2008 we inform you that yesterday, we instructed our bank to extend the validity of the L/C by 21 days.
Please note that we are not willing to assume any additional costs which might occur.
Moreover, we are not in a position to grant any further extention, due to the fact that we have already sold the goods to customers.
If you have already sold the goods to another customer, how are you going to honour your contract with this person if they pay?