It shall not be possible to create a charge over part only of an interest in a commonhold unit.
An instrument or agreement shall be of no effect to the extent that it purports to create a charge in contravention of subsection (1).
Subsection (4) applies where—
land becomes commonhold land or is added to a commonhold unit, and
immediately before that event there is a charge over the land which could not be created after that event by reason of subsection (1).
The charge shall be extinguished by virtue of this subsection to the extent that it could not be created by reason of subsection (1).