the prices quoted aren't that expensive for a main agent. engine mount and shocks are probably something that need to be changed anyway. now at least you know what has been done to your car and you know you have something that is better than before.
cheer up. may be you want to disclose the bad garage and the instructor to help others to avoid going thru' the same drama.
well, if you like the way he taught you, like yr hubby said, continue and may be he would give you free lessons as a compensation. sounds like he didn't do this on purpose. treat him extra nice so that he would feel extra guilty for what he had done.
or if he is not that kind of person that will feel sorry and you feel you have learned enough to drive from now on, get rid of him!
hope you will get yr car back soon and in good shape.
after reading all the posts, still don't understand how this problem could happen. btw, what was the brand / model of the car ? i could not see it mentioned.