I seem to recall one carrier that didn't pay their landing fees, at LHR. That was ignored for a long time, until one day they showed up with a brand new Tri-Star on an "Inaugral" bash complete with press day and fireworks. The crew for the return flight arrived at the aircraft to find a writ pasted to the entry door and a barricade to prevent push-back. Landing fees are like TV licences, they always get you in the end.
**********************************
Through difficulties to the cinema