I would not just file a report to DL, but I would file a report with the DOT... If this becomes a frequent occurrence and all it takes is one SOLID evidence [tape of an employee commenting that your bag won't make the flight, etc] and then the DOT will take this matter into their hands and impose heavy fines for extortion...

Extortion is considered FELONY even if it is a $2 extortion.

"Extortion, outwresting, and/or exaction is a criminal offense which occurs when a person unlawfully obtains either money, property or services from a person(s), entity, or institution, through coercion."

Tips are the norm here, however, it is illegal for them to FORCE you to pay tips or threaten to not provide a service they are bound to provide if you do not give any tips.