Nedbank not taking responsibility for a security breach on my business profile money App

My business profile Nedbank App was hacked on 25 October 2022. Another device has been registered on my profile without my consent or approval and Nedbank allowed it. R 15 000,00 has been de*****ed from my account. The ********* is known to the bank as the money was transferred to another Nedbank account. I immediately informed the Nedbank ***** Division and reported and opened a ***** case at SAPS. After one month’s investigation Nedbank formally informed me that they do not take responsibility for this loss and is prepared to pay an insulting R2600.00 as an ‘Ex Gratia’ payment. I am in process in selling my business ,a guest house,due to covid losses. The new owner wants to cancel the transaction due to the way Nedbank handled this case. i really feel that Nedbank has to step up and take responsibility for this loss. I am a client of Nedbank for 30 years.