Dear Khun Harald,
Thank you for you advised,
Sorry for below mail I'm not CC you because i will to discuss with Khun Sak before request warranty from you
because the customer let me know they discussed with Khun Sak can be prepare letter of warranty 5-10 years
that i will try to phone with khun Sak but not reply me,
Dear Khun Sak,
Please let me khow about story of you discussed with customer because they still waiting you ka.
Thank for advance.