Nedbank is taking advantage of elderly people

My father laid a complaint since Last year October 2022 about an R 10,900 that had missing in his account and another amount of R7 500. Nedbank has been sending my Dad from pillar to post since then and it is now 7months later they are still not willing to take accountability, every time when he goes to Nedbank he’s told they are still busy with investigations. I’m not sure what type investigation that is taking more 6 months without proper feedback and progress. Kindly assist as this is unacceptable for Nedbank to advantage of their client and this is not the first complaint my father report his missing funds and Nedbank is not willing to take accountability.