stupid bank

I went to nedbank branch to deposit money into my account. I was then advised to use an atm. I did so. Two days later i was at ultra city n i needed money for petrol and toll gates. To my surprise. My account says insufficient funds. I phoned nedbank call cenre and i spoke to a consultant who was totally useless. This guy told me it will take three days for my money to validate. Practically i have to wait there for three days.what is the point of using atm if money dont validate immediately. This is stupid