I sent you a checklist of which tests I usually perform Sharon (as a guide) included but not listed would be a visual inspection for obvious damage, wear & tear - I hope you recieved it - I have serviced MS16As and MS26s for 15 years or so and have received manufacturers training on at least 2 occasions. I hope it is some use in outlining the tests that are actually there in the manual if you look hard enough - difficult for the layperson to extract because of the erratic layout of the manual. As you can see there are quite a few steps involved. John's comments are all well and good but in agreeing that they are competent, qualified and use manufacturers spares it does not mean that contractors will actually do all the functional verification tests necessary unless you pin them down to specifics. It might be worth specifying precisely what you would like the contractor to do as part of a routine check or after repairs for example. i.e specify what you get for your money perhaps. Have you asked for a quotation or a "benchmark" figure from Smiths Graseby for return to base servicing?
I am competent, qualified, manufacturer trained and experienced but that doesn't mean I wouldn't try to do the minimum possible if somebody wanted me to quote for servicing without specifying what level of servicing they wanted. Half the tests I've listed, combined, would take less than 5 minutes per unit to do - the ones that specify delivery rate tests or thrust adjustment involve actual calibration verification (you did say you wanted to include calibration) these are the ones that can take time and that will prevent loss of delivery and incorrect rates, respectively. They are all manufacturer recommended in the manual.