Same problem I have, flights cancelled four times then ticket changed to "open" ticket and when I enquired as to what this meant I was told that it had to be used on the original routing before 30/3/2021 which in my case is AKL-SIN-LHR, as I am UK based this is useless to me as it's highly unlikely that I will be able to return to AKL before then given the travel restrictions that will be in force in NZ. I will try and do something through EU261 when I finally get back to the UK otherwise the whole value will be lost. I too was refused a refund or even vouchers that could be used for another destination.