system
A chat on subreddit /r/NoStupidQuestions
human
What can you do at the moment when you’re presented with a bill listing the extra amount with no previous communication? 

I’ve seen so many such issues lately, I’m not too worried about $5, but I’m worried about the day they put a significant amount as the extra charge. Imagine $250 cover or service fee.
gpt
How is the number presented? Is it an additional line item at the bottom of your check with taxes added to the bill?