Reason for not paying out a claim

Last year February my mother passed away and Alllife phoned to speak to her, I informed them that she passed away, they instructed me to send all relevant documents and I did.. Couple of months later they informed me that they will have to appoint a 3rd party for more investigation, the 3rd party arrange an appointment with me and sees me, the day of the appointment I ask him how long will it still takes and he said it can take up to 10 years as the government laboratory takes long for results or the hospital and did I not notice that my mother was yellow or not well, as he knew or saw my mother before and that very moment I get suspicious because of his questions, nevertheless couple of months later Alllife notify me and said they can't pay out the claim as my mother weny for a scan, I asked the lady is that really the reason for not paying out and she said yes, she went for a scan, my mom was a healthy person and suddenly passed away how would a healthy person knows he or she will go for a scan and they are healthy, Alllife did not want to disclose either the amount of the cover..