Nedbank ******** interest statement.

I have money invested with Nedbank on their Just Invest portfolio and discovered on my statement that they only give me 7.55% interest on a balance far exceeding R100 000. There advert that they give 8.25% on that balance. Their response when I queried them was that that is only on new investments which to me is completely ********* and must be ******** as the advert do not discriminate between new and existing investments.