Nedbank homeloan

I have a flexi bond with nedbank where I pay more than my instalment,I was told I can be able to withdraw the extra money that I pay whenever I need it and I went to the bank they said the money is available but I must open an account to be able to transfer from flexi to my account. I opened an account the following day but the money was no longer available on the flexi.Other banks don't do that, a friend of mine is doing the same thing but his money on flexi is always available. I called Nedbank but didn't get any assistance. Please help