Помогите, пожалуйста, с письмом на английском. Правильно ли я составила?

Dear Mr. …,

we would like to inform you about the problem with LLC “….” and we hope to get your interpretation of the situation.

Our firm produces metal constructions, gates, doors with lots of sertificates in this
line of business.
We have been discussing the conclusion of the contract on delivery gates and doors for “A” since May 2018.
As part of this work the following stages have been overcome:

• we passed certification of “R”(name of firm) with mark “4” on a five-point scale;
• we completed the assessment form of qualifications for …;
• we completed and calculated specifications on special products, required for LLC “…”;
• we created and agreed packing of goods for safe transportation and keeping goods;
• we agreed on main issues in the contract, concerning stages and terms of production, delivery and payments.

In the last three months, X supervised work with our company (Z and Y worked with him before us).
By the end of April, the terms of the contract were fully agreed, Mr. X promised to send the contract for signature.
However, in May, he stopped responding to phone calls and emails, although read receipts were coming. In the end, we were forced to contact Z and asked her to give us the telephone number of the immediate supervisor, Mr. X, in order to receive a comment on the ethical behavior of this employee. After that, Mr. X contacted us, said that we had lost the tender, and he has no other comments. He refused to provide the phone number of his boss, citing the fact that he could not get permission to do so.

Please comment on the ethical actions of this employee. If our proposal turned out to be non-optimal for you, taking into account previous cooperation in the framework of the negotiation process, we hope for feedback.