standard bank homeload double debit

I have bad experience with standard bank home loan. at first i was paying through account debit then i changed to persal derbit. the following month the bank debit twice account and persal . I went to the bank ( capitec ) to reverse the account debit . Then when i went to standard bank they told me to email my salary advice to show that i have changed debit to persal. is two years now my problem is not solved and is affecting my credit record because the second debit always bounce . Am nolonger Qualifiying any credit. I went to standard bank about this issue several times but no solution.