Money disapearing in Account

My mothers sim-card was hacked on the 10th of May and blocked for the whole weekend. Mind you she is a pensioner and was not even aware until I got home the 12th May 2019 to surprise her and take her out for Mothers day. She only realized about her sim card not working when I told her that I had been trying to call her but to no avail. when I checked her phone it said no network. I asked her when last she received calls she said Friday. Told her lets go check her bank balances as normally people hack their accounts through the simcard. when we got to the ATM her balance was still fine. She has 2 accounts on 1 card which she was told is a fixed account where she was saving her money. She went to MTN on the 13 to do sim swap and was sent to Cell C as it showed someone was using it already, when she got to cell C she was told to go to the police station to open a ***** case which she did. MTN then reversed her number back to her after 24hrs. on the last week of May she went to Capitec to reactivate her cellphone baking as she had a new simcard. She did not think to check her balance on the fixed account as she was under the impression its safe no one has access to it. On the 3rd October 2019 she went to the bank to withdraw money on her normal saving account only to realize the is no money in the account. She then decided to go inside the bank to query what is happening. She was then told all her money was withdrawn on the 12th at Night by 2 different transactions to different account. So she asked if she can at least access her fixed account as she needed that money to buy something for her granddaughter who was going to matric dance the next, only to be told that the money on the fixed account is also gone. How did anyone get access to her fixed account? She was then only told that if you save money that's less than R10000 its not in a fixed account but when she went to open the account the first time to save the R4000 she had they said it was in a fixed account. She understand the explanation about people hacking account and taking money out on the savings account but not on the fixed account. Somewhere somehow she suspects its was an inside job. The bank has since said they are investigating and till today haven't heard from them. The teller that was assisting her on the 3rd October said the is nothing they can do. Pensioners are being ****** by banks while they think their money is save meanwhile its not safe, it can go missing in blink of an eye and nothing is even done about it.