Worthless travel/cancellation insurance!

Europ Assitance again live up to their bad reputation of denying coverage on a clear case. Why buy this travel insurance/cancellation insurance when it is worth nothing?? In May 2017 we buy flight tickets for my wifes parents through Edreams to travel end of October 2017. One month later the father has an accident with a broken spine and a blood clot on top. The father need treatment in at least 8 months and therefore his doctor wrote a declaration in late June that he is unfit to fly. Hoping that the father would recover faster we waited with cancellation until 2 weeks before departure when it was clear he is still not fit for flying. After sending all required documentation to the insurance, we received rejection from Europ Assistance with the reason: "illness known on the date of booking". ??? It is quite clear that Europ Assistance has NOT read the claim in details and has NOT taken the documentation into consideration. How can we know in May that the father will have an accident and a blood clot one month later?? Completely unacceptable and worthless insurance. My recommendation is NOT to buy this insurance. It is completely worthless!