first things first.
You had a hearing at local panel i presume, and the case was deadlocked????
If so, they cannot take a dime out of your check.
Second, depite what the contract sez, check your local state laws and see if you are indemnified from loss as an employee of the company. If so, no matter what the contract sez, you cant be held liable.
IF the case deadlocked at panel, the company would have to take the case to the next level up to and including an arbitration before they can deduct any monies from you.
Also, if the company made or asked you to sign an agreement to repay, you can ask that this document or agreement be shredded or destroyed and removed from your personel file under article 6 of the national master agreement.
Remember, no matter what source of contract your read, the employee cannot be denied superior language contained in the master, rider or addendums.
Your job is to collect checks and money orders, not inspect them for legitimacy. If they have the correct amount on them, are signed by the purchaser and payable to the shipper, thats all your required to look for.
Anything else is outside of your training and job description.
The company will pay the shipper and the company will give the case over to its insurance company for loss re-imbursement.
In some states, the national master agreement allows the employee to make a choice of repayment or discipline. Since this is not a cardinal sin, why not tell them to give you your written warning and shove the 4777 up thier keisters.
Move on with life and be more careful accepting anything remotely suspicious, or better yet, call everyone of them in for guidance from a sup and put it on them.
Learn how to play the game they want to play.