Maintenance
Question answered.
I would have your invoice analysed confidentially by another organisation when you have a full breakdown of cost.
The trouble is that sometimes organisations use "trainees" on inspections and charge full rate for them, maybe this happened to you.
My own R44 had the opposite costs, my magnetos were due and my maintenance company missed them on the 500 inspection, it flew 880 hours before they were removed.
As you say the Southwest is not highly populated with maintenance organisations so choice is limited, Have you tried Rotorspan, lovely reception and service.