Old Mutual will not respect your dying wishes

My stepfather was a kind,friendly man who tried to help people even when he had little of his own. When his elderly domestic **** decided to stop working he even continued to give her a little charitable donation almost every month,when she came to visit him. He had little other than a failing business, and decided to take out a Retirement Annuity with Old Mutual mainly as a means to leave something behind for my mom as he didn't have much else to leave her when he died. He duly saved his money into the RA every month and declared my mom as the sole beneficiary on the policy. After his passing, to our complete shock, Old Mutual decided that the **** was in fact dependent on the donations she had been receiving from him and they decided to give the **** my mom's benefit from the RA, in direct contravention of my stepfather's clear and obvious intentions!!! He never mentioned the **** on the policy! This is a grievous injustice in my opinion. My mom does not have anything to her name and we are doing what we can to look after her. The money that was intended for her by my stepfather is being given away to someone who is not family, practically a stranger, not his intention at all.