Voice security feature not working!

Do you know that Investec uses voice authentication to recognize their customers when you call their call center? I had a query yesterday and I was told I could not be helped because I failed voice authentication. What is the purpose of having such a security feature if it does not work? By the way I was eventually assisted by my banker but it was such a frustrating process. Use something that works Investec and inform your customers so that we are aware that our voices are used for these purposes!