EFT payments taking too long to reflect

I cannot for the life of me understand why it takes so long to process standard EFT payments if it is all done electronically. Instant payment fees are expensive, but why if I made an EFT from Discovery Bank to my Nedbank account on Saturday afternoon, does it still not reflect on Monday?? How long do you need to sit on the money to earn your little percentage of interest before I can have access to it? I already pay nearly R200 a month in banking fees, so it's unfair that you withhold my funds for such a long period. If I made this payment to any other bank, it would have reflected by now.

I really think it's time to close my account with you.