Want to debit order more

December I took a loan from Boodle and I had to pay back R3057. This could not go off 1 of Feb, because my boss did not pay me yet. They contacted me and asked if i wanted to pay it back from 28 feb over 6 months and i said yes R909. So when my boss paid me the whole R3057 went off from my bank account, and I saw today that they wanted to debit ordered R909 yesterday after I mailed them on the 4th of Feb and said nevermind because I saw you debitted the whole amount