Before things get ugly, and he finally figures out you will never pay this extortion bill, why not ask him, politely, to please justify how he arrived at the original shipping figure and then justify how he arrived at the increase. You might send a typed unsigned letter. If later on, what letter, is it signed, I didnt sent that. Anyway, tell him that with proper justification, you are willing to consider paying - not. Knowledge is power, knowing what his offense is will allow you to counter attack or defend any black marks on credit reporting agecies. Plus you will not be blindsided by something you dont expect in the future, you'll know exactly what his claims are based on. After you extrct all usefull information, then thell this jerk to stop his extrotion attempts and all future correspondence will be through your attorney.