Dishonest company

I had a very poor experience with All Life. I opened a standard policy for my mother and disclosed that she is diabetic. They said it is okay she qualifies for a full life cover as long as that is the only condition she has. Then they said they will organize a doctor to test for any other conditions. They did and the results confirmed that she is only diabetic. They then sent communication saying that they will only cover her for accidental death only since her sugar levels were high that day. My mom is healthy besides being diabetic. Now I have been calling them and sending emails wanting to cancel the but they are sending me from pillar to post. This is behaviour is so unprofessional and I want to cancel and look for other service providers who will be honest.