files for 20,30,40,50 eur are done automatically and are not done manually...every one who sells files for that low prices, do not know how to do proper manual modification with full control over the ECU logic. But problem is mainly in consumers that think only about low price and without thinking about the quality and long term business and also long engine life. There is very little people who know how to make proper modification manually without cheating the system or turning off all error codes so ecu never reports any problem on the engine.
Now if you think logically, do you think that someone will spend hours on file for 30eur or he uses software to automatically modify the file?
I am not talking about this case but about all cases that are similar to this.