Call BS all you like. I have on occasion raced up to crew ops to try and keep an itinerary only to be told "Sorry, you're two minutes out, we've re-crewed!" I frankly DO NOT believe that you've ACARS crew scheduling and received any joy out of it, its one of those 'urban myths' and it simply don't work that way. If the crew keeps the trip then thats because its suits scheduling i.e. they're running out of crew. Our very overworked guys in crew scheduling could not risk cries of "nepotism" and I know some of them (both past and present )well. I would be interested to hear from any other Eurofleet crew who agree with you.
I have also seen some quite frankly obscene foot-dragging to avoid doing a 'charity' manchester/ncl/edi link, things like refusing to board because they found some crumbs, and have called back the cleaners to delay departure and various other 'tricks'.
Which I would hope you dealt with appropriately. Incidentally, a link by its very nature, can not be a charity flight. Only single there and backs between 1301 and 1959 qualify. All others would trigger a meal allowance of some sort.