This is a big problem for me when I can't improve my website SEO in two month of searching and applying any solution to increase my websites's SEO and the hole project faced a ruin, while a company moved my website from the end of the google search list to the first page in 20 days of working without any change in my website or causing any problem for me.
What I have done includes:
1. Article submission in article directories
2. Link submission in directories
3. Advertising on free websites
4. Commenting on different websites
5. Social Networks
6. Analyse of keywords
7. Creating landing pages
...
Now please help me to know what way is wrong and what these companies do?