Complaining in Person

I prefer complaining in person to complaining in writing. From my experience, complaining in writing ends up being a waste of time since most companies ignore these complaint letters and never reply to them. Some companies provide such a dreadful service or sell such poor quality products that makes them they get flooded with complaint letters, and they just decide not to pay attention to these complaints.
For instance, that is the case of phone companies where a written complaint is not likely to be answered at all. They have call centers to receive the complaints from customers, but most of the time the employees of these call centers are unskilled to assist not skilled in assisting customers with their needs and demands. Therefore, the only useful option left is going to a store or to the offices of the company to expose the reason why one is complaining and what solution is one is waiting for.
This situation happened to me with an airline. They lost my luggage, and the staff of the airline at the airport told me the procedure I had to follow. After sending many mails letters/emails to the company I did not get any response, so I decided to go to the headquarters of the airline. When arriving there I told one of the employees my case, and she allowed me talk to one of the managers. The manager took notes on the incident with my luggage. Two days later, the airline called me back and I got a refund to make it up for my lost baggage. All in all, complaining in person is far more useful than complaining in writing when it comes to getting a solution from the company.

Your original article is perfectly understandable and fluent, and I am just making suggestions that make it a sound a little more like a native English speaker.  The main thing that stood out was 'sending many mails'  as the plural of 'mail' is 'mail', so if you wanted to use that word you could say 'after sending a lot of mail', but 'letters' or 'emails' would be more specific.

Hope that helps.