TEN DOLLAR
The small turboprop operator should be named and shamed. Bonding for promotion is not negotiable in my view and perhaps you should have taken them to the door of the county court where they would probably have capitulated. It would have cost you virtually nothing.
The bond of £41,000 is probably not sustainable and therefore not enforceable. Anyone presented with this sort of thing should ask for the breakdown of this figure and if it is, as seems likely, unjustifiable, not sign. The problem is that once the threat of court action is made, people get worried and that is understandable. Unfortunately, it allows the perpetrators of this sort of thing get away with it and companies with a proper perspective on reasonable bonds get tarred with the same brush.
Will you name the operator or, at least name the aircraft type so that we can draw our own conclusions and let it be a warning for others?