Is it a good idea to describe the features of a product/service by making fictional scenarious how to use this product?
I know the best aproach would be to present at first the problem and show afterwards the solution. But in my case there are several problems and several solutions.
Absolutely, in fact it is probably the best way to do it. Humans respond very well to stories since they have been a very important part of our communication skill set for thousands of years.
Try to relate the stories to actual scenarios that the person you're talking to may have experienced. That will make them recall the experience and the pain they felt. This will help them connect with your story more closely and they will better understand the solution when you present it.
As long as the scenarios can happen, and are likely to, I see no problem.