Hi lebcan,
It is really sad to hear about the new medical exam request, but it makes me more sad to hear that you are fed up. We all felt this unfairness at one point or another during the process, and at some points i got so frustrated and wanted to end everything, i even got refused visitor visa 3 times, and at one point my wife was in the hospital for 3 months and they still didn't let me travel to Canada to visit her. My wife and I have been married for 3 years now, and we applied the first time on February 2012, and we faced a lot of complications and injustice, to the point where we canceled the application. Then we applied again and we had to go through the same procedure again, and we still got a feel of the unfairness.
Now after i am in Canada, we look back at it and say it was a good life experience, and we learned a lot from it...and trust me it is WORTH IT...just go with the flow, and do what they ask for, and inchalla soon enough, you will join the rest of us and be one of our Canadian fellow citizens