Incorrect Debit Date

i have a personal loan account with which gets debited on the 20th of each month. This month my installment was debited on 19/06/2015 which resulted in the payment being returned and a returned fee being charged. This has put me in a dilemma as i now have a bad credit record on my cheque account and on ITC. Being trying to speak to somebody and have been push around to eight different people and no one can assist. I spoke to Lionel in collections who was totally clueless and gave me a number to dial which does not exist. If this is what client service is to Standard Bank then you have problems. Please could someone contact me to advise how this can be rectified.