We have no way but______ask you to amend the L/C,otherwise we can not ship the goods_______ due time.

We have no way but______ask you to amend the L/C,otherwise we can not ship the goods_______ due time.

to，on。have no way/choice but to do sth．表示“除……之外别无选择，只能做某事on due time表示“准时，按时，如期”。