If its just subscription that you have to pay, try giving them a call (where your number doesn't show up), and tell them that before you left the country, you said to them that you are leaving, and they said its ok.
If they don't cooperate, just tell them that you never come back to switzerland, so its a waste for them to keep on sending papers, collection agencies, etc.
Don't know about switzerland, but in other european countries you would never get stopped at the border for such a thing.
In the unlikely* event that they bring it to court, and obviously you will be found guilty, in the street in switzerland, if randomly stopped by a cop, they could have it on file, but even that I'm not sure.
*such companies usually make an address verification, before dragging someone to court, otherwise they spend a lot, and get nothing in return.