1 Sorry we can't make any compromise due to the huge amout for this deal.Our company can only accept LC as terms of payment.
2 Since we have made agreement on prices,then we can discuss relative issues on payment terms.
3 OK then,I can do nothing but accept your requirement (or what I can do is to accept your requirement).Hope we can have happy cooperation this time,and thanks for keeping in close cooperation relationship with me and offering such low prices.