And for the 24h free cancellation: It's only free if the flight is still >7 days out, so no free cancellation short term (of course we could always book a refundable ticket or risk the small cancellation fee).
At least for flights bought from Germany on TKs German website, YMMV.

Free cancellation worked like a charm in my case, I did read all the fine print just to be sure (as stated above: 48h free reservation hold still available, BUT it's either that or free cancellation, and with free hold we can't try to upgrade since it's not ticketed with the free hold. Still a great option I used and will use many times).


24h free cancellation — but not for flights with a departure in the next 7 days, so no luck for trying a last-minute upgrade with it.