Apologies if this has been posted before, but... Has anyone managed to get any miles from the Online Booking Bonus? Every claim I do is rejected ('ticket number not found') and the helpdesk feign ignorance...

Seems to apply to me... Maybe the very last sentence is the killer:

Flying Dutchman bonus Miles are only awarded for KLM tickets booked via www.klmuk.co.uk
For a ticket to a European destination you will receive 500 FD bonus Miles, for an intercontinental destination 1000 FD bonus Miles. These bonus Miles are awarded in addition to the usual FD Miles.

Flying Dutchman bonus Miles are only awarded when the ticket is actually used.

If you use your Flying Dutchman Miles to book a ticket online, you will not receive Flying Dutchman bonus Miles for this ticket.
KLM reserves the right to terminate this promotion at any time without prior notice.