Instant payment charged but payment only went through the next day

I made an instant payment on 11 jan 2018. Proof of payment and notification says payment due on 12 jan 2018. Hoe can this be? Call centre says it must be a system error and that instant payments take about 2 hours to reflect in the beneficiary account amd should be available anytime soon. i advised that the payment went off my account but i can see it as pending. It was confirmed that the payment should be received in 2 hours. Today i receive an sms saying OVERNIGHT payment has been made. Whats the use of paying R40 for the payment only to reflect the next day? Kindly refund the charge for the error made by you. Really bad service. Feel like changing banks