Ever though about the possibility your doc wants you to take less medication in preparation of the surgery? I often had to lower my dosages before anaesthesia (my surgery usually camein cycles of several opeartions a week during a couple of weeks, one cycle in Spring and one in Fall). It reduces the chance of complications during surgery and, as you will probably get other medication right after the surgery, it will prevent you from becoming increasingly dependent. It is a common practice here in Belgium.
If this is the case, then you have a good doctor. Taken into account the limkited amount of time doctors have in some countries, I can imagine they fail to explain their reasons, they often do, even when they do have the time. Could be he told you, maybe a long time ago, your initial levels couldn't be maintained for ever. A recent study in the Netherland pointed out that patients, for various reasons (anxiety, pain, shyness, etc.), do not consciously register about 70% their doctors tell them. The doctors on the other hand take notes and often do remember. If this doc has been good for you for two years, why don't you just trust him? After all, he's the expert.
Think about it will you.
To stand and be still at the Birkenhead Drill is a mighty bullet to shew.