Effexor can be very hard to stop taking, and should be done slowly, tapering off carefully for as long as is needed for the particular person. The other issue is, did your doc think the mirtazapine was going to ease your quitting effexor, or just permanently switching you? Remeron is quite sedating, so she might have though this would help you through the withdrawal, but as its mechanisms of action are completely different than those of Effexor I don't know if that works or not.