I dont understand why old colour cable is worth more.
No one goes around checking if something has been installed and not notified, and if they did would the old colours really convice the fictional checker its an old install.
No one checks what has been notified, if i grassed up a few builders i doubt anything would happen. Not that i would know who to inform. Its the homeowner who would have the fine anyway, but im sure it can all be claimed the installation is not finished yet which is why it has not been notified.