Bring It Back Charge

This is infuriating.

After two conversations, one with an agent and one with a manager, I was told by management that the reason I'm being charged $610 for a bring it back phone is because I returned the phone to the wrong department. To the trade-in Department rather than the returns department, nowhere on the website or my contract does it say this.

How do I raise this charge further since this is on a contract?