Investment complain with Nedbank (Nedgroup investment)

I’m writing this message on behalf of my father. He has an investment with Nedbank with an amount of R300 000 with an account cold Nedgroup investment, he opted for the living annuity but now he wants to change the nature of the account, the investor is saying he is not allowed to do so. The problem now is that SARS is after him and they are saying his owing bcz of returns. My father is old and uneducated the advisor who helped took that advantage and did other wise, now my father is even sick because of this.