Dear Sir or Madam
The reason why I'm writing 
this
 letter to you is that I want to complain about a problem,which I face in your transport service every day. I have been experiencing uncomfortable and worse service for several weeks.
At the outset,the primary problem is that the company's buses come late daily and they distribute my schedule. Linking Words
For 
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this
 reason, several times I came late to my work and  skipped my important meetings. 
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Additionally
, some buses are so dirty with some rubbish like papers,and bottles, and they are incredibly slow and air conditions do not work in peak hours. I and other users cannot go to their location comfortably and safely.
I understand  that scheduling bus times is challenging work. Linking Words
However
, if you solve all these problems, Linking Words
this
 company's rate will increase.
Eventually, I hope you will solve these misunderstandings in the near future and create the most flexible timetable. 
Yours faithfully,
Murodjon QodirovLinking Words