Yes! The instructions manual just came!! Now I know how to program it. I'll post the procedure so that anybody who runs into the same problem can have the final solution.

First of all, press the mode you want to program (eg. TV). Then, all you need to do is press P+ (the button to change channels) and V- (volume controller) at the same time for two seconds. Then the indicator light will turn on; you just need to input the four-digit code and the indicator light should go off. Now you try to turn on your (in the example, TV) and if it does, you've got it!

Thank you very much Mr. Griffiths for your help. I didn't even need to call them.
Have a nice one!