If the client canceled AFTER the shop was done, I think there's plenty that ACL can do. I would expect them to make me whole by either reimbursing as the shop required OR by paying return shipping or cancellation fee for the ordered product. I've worked for ACL a long time, and I like them. But I would ask for my money.
If I'm correctly understanding what happened, this is no different than completely (and correctly?) performing a shop and starting to enter the report and it's canceled. Of course, if the order was done incorrectly and the client canceled because the order was not acceptable, that's a different story. But that's not how I'm understanding the OP's story. I think: Order done wrong, the client can cancel without payment; order done right, money for the shop is owed.
OP, I would start with contacting Chuck Paul at ACL, 888-446-5665. Good luck. Let us know how it goes. Unless there is more to this story than we've heard, I would be VERY surprised if ACL left you holding the bag with this outstanding order. And I would want to know that they did that.
And, hey, lots of ACL schedulers read and post here. Maybe we can get a comment or some information from one of them.