Below is an xtract from the onemotoring.com site:
Vehicles registered using Open Category (Cat E) COE
For vehicles registered using "Open" Category COEs, the rebate will
be based on the QP of the "Open" Category, or its corresponding
category, from the same tender exercise, whichever is lower (see
example).
Vehicles de-registered within 2 years of their registration for the
purpose of export
For vehicles de-registered within 2 years of their registration for
the purpose of export, the rebate will be capped at 80% of the QP
paid on registration. For vehicles registered using "Open" Category
(Cat E) COE, the rebate will also be capped at 80% of the "Open"
Category QP or its corresponding category, from the same tender
exercise, whichever is lower.
Does your vehicle falls under this category? Only when we get this
thing straight can I advise you further.