Home Loan deduction twice in one month. Still awaiting refund since 19 December

I an very displeased with the service I received from Standard Bank. I switched banks in December from Capitec to Standard Bank(big mistake) of which they convinced me to do. I have a home loan with Standard Bank since 2011. Due to the bank change details I requested them to deduct the home loan installment for 15 Dec of which they did do. Confirming they will not deduct the 1 December. Then after they deducted 01 December I called them that they should not deduct 15 December as already paid bond for month of December. Problem is they also deducted the 1 Dec as well as the 15 Dec and Im still waiting for my refund after several escalations. Now they refer to deceased estates because it was joint bond with my late mom. This is unacceptable Standard Bank after many enquiries and long phone calls still no refund.