I just need something clarified before I can correct your sentences. When you say "...beside the date code on the carton front mark", do you mean a kind of label on the front of the carton? If so, the correct word is 'label'.
Also, I'm unsure what you intend to say in the first sentence of the second paragraph "Ms. Ng has applied the sub-contractor". Has she called him, or hired him, or perhaps something else entirely?
Student or Learner