Which railyard did you pull it from? What was the repair for? Who authorized the repair? If it was a BNSF controlled chassis, did you call EBS or Interstar first or did you just handle the repair on your own? If EBS or Interstar didn't attempt to have it repaired first (using an approved vendor) you'll probably be left holding the bill. If you just said "screw it" and had someone do the repair, good luck. First things first, call the railyard and ask them where you send the billing to, be prepared to jump through a 12 ring circus of hoops.