Appalling customer service, never use this airline.
I received a very unclear email advising of a change in our flight details. I read it in detail and came to the conclusion that I didn't need to take any action and it was for information only. I then received another email saying that our flights had been cancelled as I hadn't responded. I spent 40 minutes on the online chat with no success then, after 35 minutes holding, managed to speak to their contact centre who offered alternative flights with slightly different timings, which I accepted. I was advised that I would receive a confirmatory email. Two weeks later I'd received nothing so tried the Lufthansa chat again. This time I was told our booking had been transferred to Helvetic and that I should check in via the Helvetic website. I tried that and Helvetic had no record of our booking. Fortunately I saw a comment that some Helvetic bookings were done via the Swissair website and found our booking there. In summary, Lufthansa changed our flight to another airline without mentioning it on the phone call. They didn't email me to confirm this and when I contacted them, they told me to check in via the wrong airline's website!