ACX, your point is completely valid.
However, at this moment, the CAA have not published a ruling stipulating compliance with AD's due at overhaul to be complied with at manufacturers stated figures.
The CAA have been accepting that, as the engine is not being overhauled yet, then these AD's are not due yet. When the engines are overhauled, then all applicable AD's must be complied with. It is the CAA's interpretation of this which is about to change, following advice from their legal department.
Those customers of mine presently enjoying TBO extensions have been personally briefed by myself giving them as much forewarning as possible of the potential ruling and its implications. This includes the potential invalidation of C of A's until compliance with aforesaid AD's.
It has also been my experience that the CAA do not extend AD's.