R100,000 ****** from FNB account. FNB not taking responsibility.

It is extremely frustrating to deal with the ***** department at FNB as my mom in law had two *****ulent transactions on her money market account resulting in over R100,000 been ****** from her account. She did not receive any notification from the bank and only when she went into her account, she realized the funds have been ******. The bank told my mom in law that there is nothing they can do! My in-laws have been FNB clients for over 30 years and trusted the bank to keep their money safe. How is it possible that the bank can simply say they cannot do anything? They are devastated and completely shocked on the lack of responsibility FNB is willing to take.