Since interfacing issues between our control panels and a/c units cannot be solved as a result of studying your product service manual, your technical staffs are invited to coordinate the issues on site. Your staffs only told us that all issues should be resolved by the product manual and refused to provide advance technical support on imminent issues before project handover.

Moreover, defect of schedule timer function has been recorded by client after handover site inspection. Your staff replied us in telephone that the function has not been provided if the requirement might not be agreed by salesman and the charge of service support for that time was waived to us in a very rude manner.

Would you mind giving some correction on my complaint article?
Ben9108Are you want to see the completely letter?

"Do you want to see the complete letter?" is the right way to covey your thought, Ben9108.

From reading the content of this letter, it seems to me sommehting is missing:

1) Details of the problem, i.e. history and when it was purchased

2) There are technical words which were misused and therefore causing confusion and continuity problems in coming across. Words likes “handover” should be “acceptance” or “delivery”.

3) Lack of fluency and wordiness.

I extracted the bulk of your letter and rewrote it as I understood. Hope you don’t mind.

After following the instructions on your product service manual a few times, the communication problem between the control panel and the a/c unit is still unresolved. I contacted your technical staff to come on site to evaluate the problem but only was told that the unit had been checked out before acceptance and refused to provide further technical support to this problem.

Additionally, the timer function was discovered not working.. Your staff replied that the timer was an option which was not required and therefore not in the purchase agreement at the time of sale. Although the service charge was waived, I am very disappointed in the way your company handles the customer issues and concerns.
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Sorry the paragraph is part of the letter. Are you want to see the completely letter?
 rishonly's reply was promoted to an answer.