I know this has come up before, so I am just trying to find out whether anyone has figured out a way forward.

I want to make a multi-city booking LHR-ZRH-CMB-ZRH-LHR, with an overnight in Zurich on the way out and way back. This is early next year. The multi city booking tool - as we know - gets me as far as the payment page, before flagging up an error. When I call, I am told ALL the flights from ZRH to LHR are full (this is for all of next February!...), so they can't price it. When I use the 'old' LH booking engine it shows only economy class flights available on the CMB-ZRH leg (which is incorrect when I look at the seatmap). When I use chat, the person I finally get through to tells me their systems are 'down' (this has been the case every day for two weeks now).

Does anyone have another workaround I can try?