Worst communication and Knieving people

I made a promise to pay R7180.76 on my home loan with Standard Bank on 24March2016 which i did. On 26 March 2016 Std Bank debited my personal accoun at FNB (the BEST Bank ever) account via debit order again with another amount of R7180.76!!! I am overdrawn now. They did this action after i have already paid my account, sent the proof of payment via email, faxed and called Standard Bank to notify them that i have paid my home loan. I have stopped the debit order via the internet banking today 27 March 2016 and WILL reverse the payment they ********ly debited against my account on 29 March 2016. My problem is that i will pay interest on my account at Fnb due to the action of Standard bank and want to claim back this interest from Std bank. I will also dscourage all people i know NOT To do any business with Standard Bank