nomorecatering someone once said ATC units always have one insanely cheerful one, one miserable grumpy one and everyone else in the middle somewhere. I work 122.4 and it sounds like you got Mr Grumpy on a bad day everytime.
Does anyone know what actions the controller does to cancel a sartime?
In ML we write callsign (sorry, ACID) and destination on rectangular pink piece of paper (emphatically NOT a 'strip' though). Then record which console (sorry, Workstation) so they know which tapes to pull if it goes wrong and your name so they know which controller (sorry, Air Traffic Facillitator) to stand down if it goes wrong. We then ring the flight data's and give them the cancelation so they can give it to CENSAR, and file said piece of paper.
Workload wise the timing of a call is as important as the length. One call at the wrong time can be a big deal if you are vectoring, many DTI positions are also have controlled airspace.
Still no excuse for being grumpy with the customers though.