I sympathise, and I would agree that if you take official advice from your tax authority on some point, that should set an upper bound on your tax obligations.

It doesn't help that bad or just plain wrong advice is given all the time by the tax authorities, at least in my country. I no longer even bother asking them about most things, because the last few times I called with a relatively straightforward business question, they still managed to give me completely wrong answers (always in their favour, naturally). The reason I know that is because when I was surprised by those answers and then took independent advice, the independent advisors used the tax authority's own official documentation to show me why what they told me was incorrect...