malfunctional meter

A very grumpy man walked into my pharmacy just as it opened on a Saturday exclaiming that his glucometer wasn't working. The pharmacist handed it to me and the other intern and it took as an hour, and about 6 test strips, to find out what value his test solution should read and to actually perform the test. The test was golden. 47mg/dl and the solution was supposed to read between 31-61. The man wasn't satisfied. I asked him about his medication history, his diet, any lifestyle changes etc., etc., etc. The pharmacist then came up and asked him the same questions. We couldn't placate him, he just got more and more upset, so I said "look, my blood sugar is always under a hundred, can I test myself on your meter?" I lanced myself and tested right in front of him and got 90gm/dl. After about an hour and a half of my time, he finally accepted the fact that his meter is working and his doc will need to bump up his metformin a little.