No refund to date

A month ago my mother returned her hired vehicle to Avis in Durban. To date she is being given the run around for refund on deposit. They refuse to release the funds and the bank said it Avis doing this.They never get back to her after countless calls either and keep saying it's going to reflect in account next day but nothing. We cannot get any management on the phone either to assist. If they do not refund within this week we are going to ombudsman which is always a great help in these situations.