buses – Old Turin bus fine never sent me the letter to pay

I am looking to try find out where and how I can pay a bus fine from a few years ago in Turin. They never sent me a letter in the post, but took my passport details for forgetting and not knowing to validate and stamp my bus ticket .
I am concerned that one day they will not let me back in the country .

Is there a way I can pay this? Or a website / contact to find an old penalty they never sent me the letter for?

Any help would be much appreciated