Home loan debit order

After receiving very bad service from Absa Private Banking, I changed to Investec Bank. Six weeks after changing my Absa home loans debit order banking details to investec, they still tried to debit it from my old Absa account. After numerous threatening emails and messages from Absa, they ensured me that the amounts will be debited from Investec. A wrong amount was now debited from Investec, and again, Absa tried to debit both home loans from my old Absa account. I give up with them.