I don't have a number for LONQF unfortunately. I know the industry here was sent a memo/notification from QF a couple of weeks ago saying the general res lines no longer assist with listing etc and gave numbers to QF Staff Travel to use for all nonrev issues, including listing.
Maybe try an Admin number for the London set-up and ask the switch operator there for a contact.

Kangaroo route embargoes on QF from my experience tend to be in the peak season, but they also appear out of nowhere as well when the backlog of nonrevs at SIN/BKK gets too big.