No personal experience, but most pharmacists can give you a "blind taper". You never know how much you are getting.
Massive Caveat: If you have take away doses - this will not work, because the law, in all its wisdom, require to have the dose listed.
I know that this worked for people before, I've spoken to several. In the end they are giving you cordial. It's possibly the placebo effect. It could mean you are really ready to get off, because every time you reduce, you are going to go through discomfort - speaking from personal experience. But when they tell you that they've been giving you cordial for the last 3 weeks, I'm sure you'd be rapt (me, I'd probably go score the biggest amount I could, knowing that NOTHING would be preventing that high I'd been looking for for so long) but that's bad HR advice, so don't do that.
It is an option though. I tried that, failed on the first reduction, well, failed equaled buying other things because I knew I was sick. Everything works for different people, and the placebo affect is NOT FAKE, it's proven. It works.