Charging interest after date of Death disaster

I am the executor of an Estate. The Deceased passed away Last year April. I reported this to the Bank and the account was overdrawn. Nedbank continued to charge Interest after date of death. The Debt doubled over a period of a few months and now they are harassing the deceased's 85 year old wife to the point whereby she is almost sick with worry. I have reported this a number of times to Nedbank but they have done nothing about it. I am at my wits end.

Can anyone sort this out or must I report this to the Ombudsman?????