Denied claim

My father passed away in 2007, I was 20 and still a student, he had a policy at old mutual and I was one of the beneficiaries, when I went to claim I was told that the claim was already done, I phoned head office and they promised me that they will investigate the matter, phoned so many times and they just kept on telling me that the matter will be investigated, dropped out of school after the passing of my father as I couldn't afford school fees anymore, and I was employed as a waitress, saved money so I could go back to school, I followed the matter to a point where I wanted to give up, because at times I would speak to rouse people over the phone from the head office, and then I recently realized that giving up is not an option because if I give up then I won't be fighting for my own children, what if something like this can happen to them, I do not want them to suffer like I did, because at this point I am old I am 31 with no insurances, not because I do not want to but because I fear that what had happened to me will happen to them and to other people as well, and recently Natasha from old mutual head office phoned me and told me that a claim was made and was paid to my step mother so there is nothing they can do about it, so what was the investigation about then? Why did they not tell me then that nothing can be done, its not like I was under age....