I'm not fully sure of your intent on the guarantee letter paragraph, but here goes:
Ruby understands that Tom had agreed to change the payment terms to L/C instead of T/T.
a) the date of agreement or
b) whether you would prefer to reply to him directly.
We had not sent any guarantee letter to Ruby for the time accuracy problem until yesterday.
After checking with Simon, the traveling cost for last inspection to xxx factory is USDxxx, the detail is shown below xxx. Please advise your final instructions
Student or Learner