I am a teacher in mathematics and science, however I am currently studying my masters in TESOL, so hopefully my advice to your problem is helpful.
The following is an edited version of the two paragraphs you have written.
Mr. Ali went to Japan at the beginning of the year. He bought a great amount of different kinds of cars. He sent one of his huge ships, with these cars, to one of the gulf countries to begin a new investment journey.
After Ahmed arrived to his country, he hired a flat. He bought an air conditioner, without delay, due to the hot weather. Unfortunately he bought a bad one and he didn't want to return it back as there was a shortage in air conditioners in the country. It was also rare to find one. He attempted to fix it and was successful.
Your sentences are too long. Try putting full stops and starting new sentences when you talk about something different.
Whenever you use the word 'then', replace it with a full stop and start a new sentence.
Hope this helped.
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