Oh and another lesson! Ensuring that each deliverable invoice is small enough that it falls under the simplified claims procedure (in the UK it’s 10,000 pounds) greatly simplifies collection.
It costs something like 80 quid to file for recovery in court and in our experience invoices are immediately paid up when a “Letter before action” is sent.
You burn the relationship, but arguably you probably don’t want it anyway.
> simplified claims procedure
I believe this is what we call small claims court in the United States. The threshold varies by state, but it is a very effective way to deal with recalcitrant companies both large and small.